Pete's Algae Scrubber for a Planted Tank

[Redbone]

I’ve had a 180 in my living room for almost 20 years.

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All of the plumbing is routed downstairs to its own dedicated room.

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I had an MMFI algae scrubber hooked in (upper left above) until about a year or so ago until it finally fell apart. I was unable to find any new scrubbers for sale, even at this site it looked iffy, so I bought three different plexiglass adhesives to try and fix up the old scrubber. But with all of the changes in technology, both lighting and design, I tossed out the old MMFI scrubber . Like I said, I would have gladly just bought a ready made scrubber, but the only one I found was here and sales didn’t look promising. I probably would’ve balked at the price anyway.

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So I set out to build one on my own. Using some of the info here I bought the lights and two 2’ x 4’ sheets of 1/4” Acrylite. $300 already, good grief.

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The scrubber is two feet long and I cut the sides and bases such that I could get them from one four foot sheet. I taped off the base prior to applying the two part Acrylic glue. This helps to align the sides and makes the build a little cleaner.

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Glued one side on and then the other.

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The two part glue is really strong. The below picture was my first attempt that I botched. I pulled on a side to test the joint strength. The plexiglass failed before the joint!

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Here’s a picture of a bad patch of joint on the new scrubber, don’t know why the bubbles.

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The rest of the joints looked like this. Probably should have let the glue sit for a minute after mixing to get the bubbles out.

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All four sides on.

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End caps on and a water test.

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There was one leak, but not at the above suspected joint. I used the super thin adhesive to patch the leaking area and the result was no leaks as evidenced above.

Time for an old guy on his own this week to stop for dinner.

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Time now to install bulkheads and light holders.

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Next the input water tube.

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And the lights.

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Pretty simple, really, but the plexiglass is hard to work with. It warps and is not true. You really need jigs to do it clean.

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Done, finally! Total cost is around $400, more if you include tools and the blade.

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Then of course, I had to plumb it into the system. I don’t have to worry about light leakage since it has its own room, and that lets me fiddle around with the dimensions as well. The main objectives are usefulness and ease of cleaning. The MMFI scrubber was a real difficult to clean.

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And a movie for you.


http://www.snekpete.com/Scrubber/Srub_short.wmv

[SantaMonica]

Welcome.

Nice acrylic....

[Floyd R Turbo]

Nice acrylic work but dang how much for 1/4"? I buy 4' x 8' sheets of 1/4" plex-g for $150!

Looks sized for tank volume not feeding, have you read the new guidelines?

[Redbone]

Sorry, but I don't pay any attention to guidelines. Everything is trial and error. I bought the sheets from USP for ~$50 a piece, so $150 for 4'x8' sounds about right. Shipping on a 4'x8' is prohibitive. Might have been able to find a local distributor, but $50 for shipping I can live with.

[Garf]

That's a big screen! Are you feeding lots? They are real plants in your DT aren't they? Nice build but are you sure you need a Mega scrubber ? Sorry for questions, just curious.

[Redbone]

Real plants indeed! I built it large because you can always adjust the scrubber by lenghtening or shortening the lighting cycle. Also, I wanted to be able to run the entire flow from the pump through the scrubber. As it turns out, I will need to replace the bottom drain bulkhead with 1" instead of 3/4" as the total flow from the pump tends to fill up the scrubber. But that will wait. The larger scrubber allows for more fiddling. It will be interesting to see the rate and amount of growth. Like I said the tank has been set up continuously for over twelve years now and with constant water changes and fertilizing it needs a big scrubber.

[Floyd R Turbo]

Well the current guidelines are not trial and error, they are established and accepted. The old guideline was 1 sq in per gallon of water of tank volume, the new one is based on volume of feeding, 12 sq in per cube of food per day lit by a total of 1W per sq in of screen (LxW) split between both sides. You're looking at a screen that can handle >10 cubes/food per day, and unless you're feeding at least half of that, it won't grow green very well. It will still filter, but the smaller feeding based sizing method results in more green growth faster and more consistently, and green algae does the best filtering. A scrubber that large with that much light on it is going to be an order of magnitude more efficient than your old one, and will likely out-compete your plants. Those are my concerns. Not knocking your design at all, it looks very well constructed, just making sure that you know what to expect or watch out for. FW scrubbers grow much faster also. You might want to keep an eye on plant health and adjust the photoperiod down if you need to, I would say that is the #1 thing to do.

[Redbone]

Well, I've got about 200 gallons total water volume. By the old guidelines that's 200 sq. In. The screen mesh is 12" x 18" = 216 sq. In. Better a little big than a little small. And with aquariums, each setup is unique. It is more art than science. I have a mixture of well and RO fed in, about 7 gallons total per day. The quality of the well water varies throughout the seasons. I suspect that the plants will do better with the scrubber because it will allow me to add more fertilizer. We'll see.

[Garf]

Redbone - I am now officially baffled. So you have made a scrubber to mop up fertilisers that you have intentionally added to the system? Why don't you just add less ?

[Redbone]

Redbone - I am now officially baffled. So you have made a scrubber to mop up fertilisers that you have intentionally added to the system? Why don't you just add less ?

Planted tanks are by far the most difficult freshwater tanks. The balance of nutriments necessary for healthy plant growth versus promoting algae is a tightrope and is constantly falling out of balance. Cut back to reduce algae and the plants suffer. Add too much and the algae takes over. A scrubber really helps by having the growing algae in the scrubber compete with the algae in the tank. Although the plants and algae compete some, it is not like the competition between two algae . Plants, especially the different varieties that I try to grow, have very different nutriment needs from each other and from different algae.

Also, I forgot to mention that plants, depending upon the variety, get most of their nutriments from the substrate, especially swords and lillies. Trace elements mostly come from the water column. Algae get all of their nutiments stricly from the water column.

[Garf]

That's why I love this site, I learn something new every day, cheers redbone.

[Floyd R Turbo]

Well, I've got about 200 gallons total water volume. By the old guidelines that's 200 sq. In. The screen mesh is 12" x 18" = 216 sq. In. Better a little big than a little small. And with aquariums, each setup is unique. It is more art than science. I have a mixture of well and RO fed in, about 7 gallons total per day. The quality of the well water varies throughout the seasons. I suspect that the plants will do better with the scrubber because it will allow me to add more fertilizer. We'll see.

I can understand how bigger is better would make sense in most cases. However for scrubbers this is not the case, and that is one of the reasons why the sizing guidelines got shifted to feeding-based. There was a pattern that developed with screens not growing correctly and the solution in most cases was to feed more, which usually resulted in the screen greening up. Then there were people with very large systems that built under-sized scrubbers that easily handled the bio-load. Soon it became apparent that sizing based on tank volume was the wrong method, and logic led to the conclusion that since food is the only input to the system, that the algae would grow only proportionately to the input to the system, and tank volume had absolutely nothing to do with it.

When your screen is too large, the algae is encouraged to 'spread out' across the entire substrate (screen) and basically starves itself, it will grow yellow or caramel colored and spongy, or brown and slimy, at least with SW. Not sure what the end result is in FW actually. Usually the fix is to increase feeding, add iron, increase flow, etc. But the bottom line is that your horizontal scrubber (I'm vaguely familiar with that model) was likely 1/10th as efficient as your new waterfall scrubber. So with the same or more surface area and better lighting, on both sides, I just think you're going completely out-compete your plants wicked fast.

But then again, like you said, they get their nutrients from the substrate mainly. So does this mean that you inject the ferts into the substrate?

The last tank I had before switching to SW was a heavily planted heavily stocked FW 55g and I loved it, so I'm jealous of your tank because it is very beautiful!

...and not to plug my own devices but did you see the LED version I make (link in signature)? You posted the pic of the SM100 but that's not currently being made right now anyways...

[Redbone]

Floyd I did see your algae scrubber, but I am still wary of the LEDs. I have 240 7 watt C9 Christmas lights that I set up each year, and I'm still waiting for the LEDs to get bright enough to replace the incandescent C9s. So far, I've been able to replace the blue incandescents with LEDs because the blue LEDs are the brightest and the blue incandescents are the dimmest, but the red, orange and green LEDs are still just too dim. But lighting, like batteries, is moving forward in leaps and bounds. These T5 HO fluorescent tubes are impressive, both in total output and spectrum. Spectrum is where I find the LEDs lacking, they tend to have narrow output spectrums, where the fluorescents can have multiple bands by mixing phosphors.

I know that this scrubber is going to be way more effective than my old MMFI. The MMFI had 4’ x 4” = 192 sq. In of screen, lit by two 40 watt T12 fluorescents. The new scrubber has over twice that amount of screen because it has two sides and it has twice the amount of light. It should be twice as effective. The unknown for me is the MMFI scrubber was a submersed screen, the new one is immersed. I really doubt that this new scrubber is too big, but I can always trim the screen hey? And adjust the photo period. Right now I’m starting at 12 hours a day alternating opposite the tank lights.

Although I do have some bio-load from the fish, most of the load is from the daily input of well water and the bi-weekly plant fertilizers. I’ll post pictures when I get some growth.

[Floyd R Turbo]

They're out there, you just have to know where to look and be willing to spend the $$. My buddy's house has color-changing LEDs during Christmas that you can see from about a mile away.

When you are comparing LEDs, you have to remember that you need to compare apples-to-apples. Equating the comparison of C9 Incandscent X-mas lights and low-power LED X-mas light to the comparison of T5HO 2700-3000K Grow Lamps and 660nm Deep Red High-power (3W) LEDs is not apples-to-apples. I can understand how you're not 'sold' on LEDs, but Christmas lights and HP LEDs on stars are not in the same league.

As far as the narrow spectrum, you say that like it's a bad thing. The point is that you want to use a specific spectrum! Look at Chlorophyll A and B peaks and that's all you really want to hit, the rest is wasted bandwidth. You can find hundreds of LED plant growth lights with 660 and 455 LEDs and that's it, and then outperform every other type of growth light, so much so that the vast majority of that industry has shifted to LED. Scrubbers are able to pick up on this and utilize the same principles, since chlorophyll is chlorophyll. Things are exactly equal, but pretty much.

Search for the LED scrubbers and you'll see some of the best, greenest growth.

Anyways sorry I got off on a rant there...didn't mean for any of this to come off on the offense or defense...

[sklywag]

I'd like to see about a hundred Neons in that tank.

[Redbone]

I'd like to see about a hundred Neons in that tank.

The problem that I have with small fish though is that they end up in the skimmer overflow. I've given up on them.

Took this pic last night.

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[Floyd R Turbo]

Now I'm really jealous. Gorgeous

[kerry]

Very nice!!

[Devaji108]

great looking tank! good to know there are ppl out there willing to try ATS on planted tanks. I am building one for a mixed reef w/ marine plants so a SW planted tank with corals :).
please keep us posted on the growth and over all performance of your scrubber.

[Redbone]

I'm in Maryland where we took the storm hit Friday night, very impressive lightning display. Lost power for three days. I was worried that without water flow the algae scrubber would rot but it did fine. This waterfall scrubber actually held up better than the MMFI submersed scrubber through a no flow event, I was pleasantly suprised. Here are pics after one week, actually a little longer but three days of no power. Interesting that the algae is sparse directly in front of the lights, and denser above and below.

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[SantaMonica]

Glad it survived. Once it fills in the bald spot should go away.

[Redbone]

Filling in nicely. Survived another power outage. I'm doing a couple of small updates this weekend, a new lid and then change the drain tube from 3/4 to 1/1 inch. Will get to see how easy it is to clean in another week or two.


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[Floyd R Turbo]

Nice!!

[Redbone]

Decided to clean the mesh during a slight upgrade yesterday. Cleaning the mesh was a breeze. I had to place a cross beam on the lid to prevet warping and put in a one inch drain to handle the entire flow of the system. I am happy with the new scrubber. Had I known, I would have replaced the old MMFI years ago.

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[Garf]

Let's see if you can hold it out at arms length in a few months time, when it's really going !!

[khwaja]

the plants are unaffected? that is with proper ferts i guess

[Redbone]

It appears that there is some question as to why an algae scrubber would be used in a freshwater planted aquarium. This is a difficult question to explain for two reasons. The first reason is that the explanation is really complicated and covers a lot of ground. The second reason is that some well accepted preconceptions are false. I am going to address these issues here, in a series of posts, moderators willing. Comments, questions and disagreements are welcome. Let’s see what happens.

Some of the false preconceptions are:

1) Fish help plants. False. In an aquarium, fish are detrimental to plants. They do not add enough CO2 to be measurable or affect the plants, and they do add waste products that are not needed by and are detrimental to the plants. Their food and waste contribute to algae growth without helping the plants, and these wastes tend to cause the substrate to deteriorate and go anaerobic. Aquarium plants need very little of the big three macros, NPK, and more than enough of them is provided by any water supply commonly found in the USA.

2) Airstones and fountains help tanks and ponds. Mostly false. They are of use to oxygenate water and provide circulation, but that’s it. When water comes from sources like rain, ground, streams, and even muni supplies it will contain either CO2 or SO2 in significant concentrations. These gases, particularly CO2, are easily dissolved and expelled. They occur naturally as the byproducts of bacterial action, aerobic or anaerobic. Take a glass of any freshly drawn water and measure its pH. After sitting open for 24 hours the pH raises a point or more from the CO2 gassing out. CO2 dissolves very easily in water, but it gasses out just as easily. Adding airstones or fountains to ponds and aquariums is only of use in fish tanks as it kills plants which ultimately do a much better job of oxygenating the water. Any disturbance of the water causes the CO2 to gas out, the bigger the disturbance the larger the gassing out. A typical airstone will purge all of the CO2 from an aquarium in 24 hours. Why doesn’t an airstone add CO2 from the atmosphere? 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.039% carbon dioxide, that’s why! The amount added from the atmosphere is too small to measure.

3) An algae scrubber hurts plants. False. Discussed later.

Now let’s take a closer look at water. Anywhere in the USA the water, either municipal or from the ground or streams contains elevated levels of Nitrogen. This is a direct result of people, their wastes, their pets, their farms and their lawns. You can’t get away from it. Depending upon the source, there will also be salts, calcium and magnesium carbonates, iron, copper and other trace elements. Most of these compounds and elements are in too great a concentration for an aquarium. And most often, other trace elements like chelated iron, other metals and boron are in too low a concentration. In any case, needed trace elements will be quickly depleted and toxic trace elements will quickly accumulate in a closed system like an aquarium.

TBC

[Garf]

Nice info, when's the next instalment ?

[Floyd R Turbo]

Looking forward to the rest.

One correction though, if CO2 gasses out of water, the pH would rise, not fall.

[SantaMonica]

CO2 dissolves very easily in water, but it gasses out just as easily

I think what you mean here is CO2 does not dissolve easily, which is the reason it's hard to get CO2 into the water.

[kotlec]

This info deserves separate topic at least.

[Redbone]

Looking forward to the rest.

One correction though, if CO2 gasses out of water, the pH would rise, not fall.

You are correct, raises toward alkalaine. Edited to correct.

[Garf]

I think what you mean here is CO2 does not dissolve easily, which is the reason it's hard to get CO2 into the water.

There are countless numbers of reefers that would disagree with this when combating low pH !!

[Redbone]

I think what you mean here is CO2 does not dissolve easily, which is the reason it's hard to get CO2 into the water.

No, CO2 dissolves very easily in water, much easier than Oxygen which is quite difficult to get dissolved. The reason that CO2 cannot be added to water by using an airstone is because the atmospheric concentration, at 380 ppm, is too low to make any difference. More CO2 is expelled from the agitation than enters from absorption.

The reason that CO2 dissolves so easily is that it actually changes chemically, into carbonic acid. I'm not well versed on this, I could look it up, but the gas, CO2 dissolves incredibly well in water. I found this by experiment when testing different diffusers with a 20 pound tank of CO2 in my system. A cubic foot of pure CO2 can go into the water and be completely dissolved in about 2 seconds at 15psi! Air, on the other hand, would never come close to this, it would take hours to get that much air in solution.

[Garf]

Not sure about the 2 second dissolving time because I was only aware of a 23 second half absorption rate, but yes Co2 is easily dissolvable as I have proved recently. The problem is that most carbonic acid is almost immediately turned into bicarbonate and carbonate ( depending on the pH ). I assume that this is less of a concern with freshwater systems as the pH is lower enabling more Carbonic acid to exist. And again Co2 it removed from the system relatively easily by aggressive aeration or turbulence. A balanced system is where as much Co2 is being dissolved as is being expelled.

[Redbone]

Not sure about the 2 second dissolving time because I was only aware of a 23 second half absorption rate, but yes Co2 is easily dissolvable as I have proved recently. The problem is that most carbonic acid is almost immediately turned into bicarbonate and carbonate ( depending on the pH ). I assume that this is less of a concern with freshwater systems as the pH is lower enabling more Carbonic acid to exist. And again Co2 it removed from the system relatively easily by aggressive aeration or turbulence. A balanced system is where as much Co2 is being dissolved as is being expelled.

I watched it happen, the CO2 going into solution, real time, quite impressive. The exact amount and pressure and temperature are estimates, but it was a bunch and real quick, visible through a one quart reactor that I had spliced into the discharge side of the pump, in front of the filter and the heater. It kind of shocked me as I was fooling around and accidently put a blast from the high pressure tank into the diffuser, whoops, and expected a big discharge of air into the tank, but the CO2 just dissolved magically away in a second or two, not one bubble into the tank. Probably shocked the fish, though.

As I progress on this rant it should be noted that none of this applies directly to salt water, I am staying strictly with fresh water. Salt water adds complexity, the physical characteristics of the water change as the H and OH ions in the water are weakly bound to the Na and Cl ions. Some of the ideas transfer a bit, but salt is a different beast. Further, I have never attempted or experimented with salt water so I have no experience to draw upon there, and that is where my strength is.

[Redbone]

Part II -Water

The first step to a healthy aquarium is to add water daily. But if water is added, in significant quantity, daily, water will also have to be removed. Daily water changing is the most important maintenance on a closed aquatic system. If there is not an automatic mechanism to execute the water exchange, it will not be done on a daily basis by the hobbyist, period, end of story. The percentage of water to add daily will vary depending upon the aquatic system, the input water and the automatic exchange mechanism. A rough estimate is around 5% addition of water to the system daily. If this is translated to 20% to 50% per week that is certainly better than not changing the water at all but not nearly as beneficial, especially to aquatic plants, as smaller daily additions. The mecanism that I use relies on water timers to feed in charcoal filtered well water and RO’ed water in roughly a 50/50 mix. As the new water feeds in, the level in the holding tank rises and the excess drains out of an overflow. When the well water feeds in, I can see a significant increase of bubble formation by the plants, which is a result of the high level of natural CO2 contained in the well water. The effect lasts for about an hour. Other hobbyists have probably noticed a similar effect after pouring in new water to an aquarium with plants when doing a water change, unless they let the water sit overnight to remove chlorine in which case the CO2 is also gone.

After changing the water, the quality of the input water is of the next level of importance. In general untreated municipal or untreated well water cannot be used exclusively. Doing so results in brown, red and bright green algae, the bright green stuff really being cyanobacteria with the distinctively fishy smell. Most plants will not tolerate this water, for various reasons, and will gradually die. So what about RO’ed or distilled water? I’ve tried both and pure RO’ed or distilled water will quickly kill almost all plants and fish as they both need some salts.

Use a good water test kit, once, to see what kind of water that you are dealing with ‘from the tap’. As mentioned before, it is going to have elevated levels of nitrogen, measured as nitrates and nitrites. Check for phosphates, less likely. Check the iron and copper levels. My water has a fair amount of copper which is toxic to the plants but even more toxic to some algae. The iron will not be in a form that is useable by the plants. Test for hardness but all that I recommend is using a conductivity meter which simply measures the electrical conductivity of the water in microsiemens. It is measuring the ion concentration, most of which is salts. Experience shows that between 200 and 400 microsiemens is ideal. Pure RO’ed water is about 20 microsiemens. Don’t get fixated on parameters, they can fluctuate and are not absolute. I don’t pay any attention to ‘general hardness’ and ‘carbonate hardness’. Do not make large changes to the conductivity and pH, particularly the pH, it is a losing battle. Reactors, dosers, softeners etc. are all losers, stay away from them. Work with what you have. If the house has a water softener hooked up, the house water is unfit for an aquarium, period. An aquarium will run fine between 250 and 400 microsiemens with no observable differences between high and low to the fish or plants. pH ranges between 6.8 to 7.5 are great, but don’t force it with acids like phosphoric. Typically a 50/50 mix of RO/tap water will get you into this range. Again, work with what you have and make automatic water additions, the parameter changes should take days or weeks or months to develop. Water as alkaline as 8 and as hard as 600 ms is just fine for most fish and many plants, some prefer it. Filter the tap water through a charcoal cartridge to remove nitrogen, phosphates and heavy metals. The charcoal raises the pH slightly. CO2 will more than counter the charcoal pH rise, but CO2 is not mandatory for a planted tank, it just helps.

So now we have a bare aquarium with mixed RO and filtered tap water being changed daily. It will take a week for this system to stabilize, for the bacteria to colonize and for everything settle out. If we add light there will be algae. Brown, red and bright green at first but it is the light green, both stringy and crusty stuff that is preferred. If the tank can grow good light green algae, it can grow plants.

12 hours of light a day is plenty. Adjust the RO/tap mixture so that algae growth is controlled under consistent lighting. Two week glass cleaning intervals is a reasonable goal. By adjusting the automatic water changes and controlling the quality of the water, this basic aquatic system is stable, healthy and sustainable for years. A mechanical filter is of little use. It won’t do much harm, if cleaned regularly, but it doesn’t do much good. Most filters are used to provide good circulation, which is extremely important, but the mechanical filtration can be exclusively handled by a simple sponge filter cleaned weekly. Either way all of the fancy filters and reactors are mostly products of advertising campaigns. Bacterial filtration and reactors are way over rated.

TBC - Next up is gravel, heating, lighting and nutriments.

[Floyd R Turbo]

Great info, again. Why not water softeners though? I seem to recall that use of softened water was OK. I ran a planted tank for years using it.

Also IIRC the RO tap goes on the pipe after the softener, but that is irrelevant to the information you presented - just worth mentioning.

So this info is great...but I'm still waiting for the turn of the road where an algae scrubber works with a planted tank, when can we expect that? Because that is something I definitely want to hear about.

[Redbone]

Great info, again. Why not water softeners though? I seem to recall that use of softened water was OK. I ran a planted tank for years using it.

Also IIRC the RO tap goes on the pipe after the softener, but that is irrelevant to the information you presented - just worth mentioning.

So this info is great...but I'm still waiting for the turn of the road where an algae scrubber works with a planted tank, when can we expect that? Because that is something I definitely want to hear about.

1) Reactors, dosers, softeners etc. are all losers, stay away from them.

2) If the house has a water softener hooked up, the house water is unfit for an aquarium, period.

Not sure which statement you are referring to. 1) is just a general waste of money/time. 2) is actually harmful. Whole house water softeners (most of them) work by adding salt to the water, potassium chloride, forcing out the calcium and magnesium carbonates which are considered 'hardness'. The potassium chloride is worse for aquariums than the calcium or magnesium carbonates. This is also why I recommend using a conductivity meter and disregarding all of the GH/KH stuff.

I seem to recall that use of softened water was OK. I ran a planted tank for years using it.

Aquatic systems are variable and complex, there will always be exceptions and folks that have different results. What I am outlining is something that will work for everyone and is easy to recreate.

[Floyd R Turbo]

It was the latter. Thanks for the clarification. If I ever decide to do another planted tank, I will consider following this advice/method.

I have a customer for whom I built a 70G sump for a planted tank, he was using a high rate dosing method along with and automatic water change system, I think it was called an overdosing method or something? Anyways not to derail this thread but his thread is here: http://www.plantedtank.net/forums/showthread.php?t=165053 would you consider this a "doser" method you refer to in #1?

[Redbone]

With all due respect, I ain't gonna read through that whole thread. I'll cover some of this in the gravel section, but in a nutshell here is the bottom line:

If you add dirt, clay, laterite, ADA, etc, etc, etc to the gravel you will eventually have trouble, for multitudes of different reasons, some serious, some fatal and some minor. If you add nutriments to the water in anything more than trace quantities the same applies. There are an infinite number of combinations of nutriment supplements and gravel additives, and there will be varying degrees of success and failure with each variation. But they will all fail sooner or later, none of them are sustainable in a typical non-commercial aquatic system. Some combinations will actually do spectacularly well for a period of time. I once grew an amazing lace plant in a 5 gallon water jug filled with peat moss and gravel. It crashed and burned after about 3 months, but did really well for that time. This was after the plant had been in an aquarium for quite awhile. 30 years later I have finally, by trial and error and a little research learned how to grow lace plants. A cold resting period is pure fantasy.

What we see on the internet is only the really well for that time. You don’t see the crash and burns. These folks are chasing the needles. They are adding a bunch of N or P or K and get a growth spurt. Add CO2 or iron, another growth spurt. Change something else, another growth spurt. None of it is sustainable and it always crashes and burns. It’s like a random walk, they never get anywhere but are always trying something different, changing directions. What I am working on is a sustainable system in equilibrium, no magic, no sales, no BS. A tank that doesn't require intense maintenance.

[Floyd R Turbo]

What I am working on is a sustainable system in equilibrium, no magic, no sales, no BS. A tank that doesn't require intense maintenance.

What I love about this is that it sounds like

1) doesn't use any media which requires replacement
2) doesn't sound like any technique I have heard of
3) it might actually work
4) it will tick a lot of people off.

I see the "that won't work" crowd getting all up in arms over this one LOL

[SantaMonica]

Doing so results in brown, red and bright green algae, the bright green stuff really being cyanobacteria with the distinctively fishy smell.


Filter the tap water through a charcoal cartridge to remove nitrogen, phosphates and heavy metals.

Well of course, I'm going to say that these nutrients are not being absorbed fast enough by the plants because plants are slow growing; (centimeters per month). Algae growth, however, can be measured in doublings per day; this aspect can help control the nuisance algae that grows from tap water.

[Floyd R Turbo]

Eagerly awaiting more Redbone! Did you get sidetracked, or was this thread the sidetrack?

[Redbone]

Part III – Gravel
The best book for the time (1985) on freshwater aquariums was Horst and Kipper’s “The Optimum Aquarium”. In their book they made some ground breaking discoveries or at least uncoveries, the most important being to focus on what is naturally occurring in the world and analyzing how to best reproduce that in the aquarium. This led them to pH control through CO2 management and substrate management. For freshwater planted substrate, they had two main propositions to mimic what they had found in the wild. One was heating, the other was laterite enrichment. I have read three or four other books on aquariums and to this day theirs is the best book that I’ve found on the topic.

The substrate is by far the most complex and difficult part of an aquarium. The big issue is that it is permanent, it cannot be replaced or changed without tearing down the aquarium. As noted earlier, naturally occurring ground water contains either CO2 or SO2, produced by bacterial action. This water percolates into streams, rivers and lakes through the substrate or stream bed. Runoff water does not contain as much CO2, although it does have some. Natural stream beds have a small amount of water flowing either into or out of them, replenishing CO2 and nutriments, and keeping the substrate from going stagnant. The amount of water percolating through the stream or river bed is underestimated. Runoff water from rain subsides within hours, it is the groundwater percolation that keeps streams and rivers flowing. The notions of young and old aquaria all pertain to the age and condition of the substrate. As the substrate ages it will gradually change the chemistry of the aquarium, eventually reaching a toxic state. The longest that I have personally kept a tank in continuous operation without a tear down is twelve years. As an aside, I believe that there is also water percolation through ocean reef sands. I noticed a large flow of cold fresh water flowing from the sands just offshore Cape Hatteras one sunny summer day while I was sitting in the shallow water.

In an aquarium there is no water movement through the substrate. This problem was first addressed by cleaning the gravel using siphon tubes. This is very destructive to the aquarium and is only appropriate for a fish only tank, in which case it is recommended not to use any gravel at all. For reasons that I do not fully understand aquarium gravel does not like to be disturbed. This has to do with the really slow metablolism of the organisms that will naturally inhabit the substrate. Disturbing them kills them and they do not recover quickly, which allows other bad things to happen. The undergravel filters that were popular for awhile were complete failures, both using in flow and out flow. The reason is that they disturb the substrate to much too large a degree. Horst and Kipper addressed this issue by recommending substrate heating using low wattage heating cables. Heating cables do no harm, but are also of little value. An exception being very cold environments where the bottom of the tank is likely to get “cold feet”. This can happen when the room temperature is ten to twenty degrees less that the water temperature of the aquarium. In that circumstance heating cables are recommended.

But what optimally is needed is a very slow, gentle percolation of water through the gravel, similar to what occurs in nature. Horst and Kipper believed that heating cables could effect this, but having tried them I disagree. It appears that the cables only work when the temperature gradient is large, which is only true when the outside air temperature is much lower than the tank water temperature. The substrate is a tank’s true biological filter, although it is really more of a biological reactor. Even in a pristine, unoccupied tank the gravel will accumulate detritus. The junk accumulates from bacterial action and waste, and stuff settling and precipitating out of the water. Now add fish and plants and the tank has actual dirt accumulating in the substrate. Soon the biological load will accumulate and over time go anaerobic and poison the tank. This is manifested by black and brown algae characteristic of “older” tanks.

My best efforts at managing the substrate have resulted in some observations. Do not try to clean or disturb the gravel, this causes more harm than good. I have not tried using sand, but it may work in some applications. An advantage of sand is that it resists penetration and thus accumulation of particulates. The major drawback of sand is that it also resists percolation of water and is thus stagnant, which is not too bad if there is no organic penetration, but bad for plants. If I were to set up a saltwater aquarium, I would try running a couple of small tubes under the sand to trickle in fresh water which would then percolate and rise through the sand by its natural buoyancy. In a freshwater tank the gravel should be inert, crushed and rounded granite. I have found a grain size of approximately a quarter of a centimeter works well. Too large and there is too much particulate penetration, too small and it has too high of a resistance to percolation. Do not use undergravel filtration. Heating cables are unnecessary. What I do recommend is a pump. The pump provides water circulation and prevents temperature stratification. A simple jet pump will suffice. In a larger set up I use an external high pressure pump. This has several features. It draws water from the surface keeping the air boundary clear of films. The pump also draws some water from the bottom of the tank keeping temperature and non dissolvable particulates uniformly distributed. It also allows me to automatically adjust and replace water and it runs the algae scrubber. And finally, the pump provides a very small pressure differential in the gravel allowing for a natural percolation of water through the substrate. This is accomplished by running the return lines under the gravel for the length of the tank. The return lines discharge just above the substrate surface, but in the substrate the lines have small perforations to allow a very slow diffusing of water through the gravel. It must be stressed here that any large movement of water through the gravel is destructive, the water movement through the substrate should be slower than osmosis. Exactly why such a slow movement is necessary is still somewhat unknown. It is probably that the type of bacteria that naturally populate substrates have very slow metabolisms and are intolerant of fast change because those conditions do not exist in nature.

Finally adding gross supplements to the gravel is also destructive for several reasons. Mostly they just gum up the works, restricting percolation and strangling the substrate reactor. But more subtly, supplements alter the natural chemistry of the substrate reactor and its inhabitants, causing unpredictable consequences, usually fatal. Supplements can have beneficial short term effects, but always crash in less than a year. Horst and Kipper, and many others recommend adding laterite to the substrate but after much experimentation I do not. Laterite is not too harmful but it does cause iron precipitation problems and is not all that beneficial to the plants. A brand new aquarium will require poking in some supplements around the plants, and even established aquariums benefit from this from time to time, but moderation is the key. A few balls of laterite poked into the gravel twice a year is more than enough.

Moderation is truly the key. Fast or large changes are destructive. Most plants and organisms will acclimate to a wide variety of conditions but consistency is the key. The aquatic system needs to be pretty stable day after day, month after month. Look for changes, like water chemistry or algae growth, to occur on a monthly scale. not day to day. Daily or weekly changes are harmful. This is not to say that a large water input is harmful or even unnatural, it is not. But temperature changes, water changes, nutriment and chemistry occurring on a large and frequent basis are harmful. Slow moderate changes are preferred, and the substrate is the slowest of them all. The substrate is like a really slow worm, feeding and digesting at slower than a snail’s pace. The substrate is not able to accommodate large or sudden changes, and it prefers a natural composition to an artificial supplemented one. The substrate plods on slowly, but is key to a healthy tank.
At last the algae scrubber!

TBC

[Floyd R Turbo]

Interesting

So you actually run the return plenum under the gravel bed, with the "jets" poking up out of the gravel, and then have additional smaller jets pointed sideways/down into the gravel bed? Did I understand the physical concept of that right?

[Redbone]

The return lines run under/in the gravel for the length of the tank. They feed the return water out of covered openings above the surface of the gravel where 95% or more of the return water is discharged. The 8 feet of pipe below the gravel surface has small holes in it allowing the higher pressure water inside the pipe to exit, very slowly, into the gravel bed. This creates a slight pressure differential between the gravel bed and the surface of the gravel.

It is a very slight pressure resulting in a very small flow, like I say, slower than osmosis. The main return openings are an inch or two higher than the substrate holes in the pipe, so the pressure at the return openings will be less than than the water pressure deeper at the holes in the lines. Actually I don't even care which way the water moves as long as there is a very small gradient or movement of water in the substrate.

[SantaMonica]

For reasons that I do not fully understand aquarium gravel does not like to be disturbed.

One of the reasons is periphyton, especially sponges, which have positioned themselves to intercept available particles and light. When you move them even slightly, their supply of food and light are cut off.

[traxiii]

It's funny, I've been using an under-gravel PVC grid to return a portion of the return water from my sump in my las two tanks. In my 100g I think there is about 35' of 1/2" PVC with small 1/16" holes facing diagonally down from the pipe. I run mine with a bit more flow, it has a 250 gph pump hooked up to it, where it climbs 5' over the rim of the tank before plunging down below the gravel. The rest of the return goes to the surface via a 800 gph pump to disturb the surface, though a small portion of that runs to my up-flow algae scrubber in a closed loop returning to the sump.

[Scatocephalus]

The return lines run under/in the gravel for the length of the tank. They feed the return water out of covered openings above the surface of the gravel where 95% or more of the return water is discharged. The 8 feet of pipe below the gravel surface has small holes in it allowing the higher pressure water inside the pipe to exit, very slowly, into the gravel bed. This creates a slight pressure differential between the gravel bed and the surface of the gravel.

It is a very slight pressure resulting in a very small flow, like I say, slower than osmosis. The main return openings are an inch or two higher than the substrate holes in the pipe, so the pressure at the return openings will be less than than the water pressure deeper at the holes in the lines. Actually I don't even care which way the water moves as long as there is a very small gradient or movement of water in the substrate.

One of the more successful plants tanks I ever had incorporated a plenum with a very small heater (15 watts) under one end of the plenum. This caused the warmer water by the heater to slowly diffuse up through the gravel on the end by the heater but pulled cooler water through the gravel at the opposite end. Many of the nutrients that would normally be in the water column were pulled down into the gravel where the plants could utilize them.

[apodistagon]

... At last the algae scrubber!

TBC

What a cliffhanger. I'm new to freshwater planted tank. And I really wish to try using an algae scrubber.

Redbone, I hope you'd return one day and share with us what you know about algae scrubber in freshwater planted tank.