Scrubbers compared to refugiums

[SantaMonica]

Scrubbers compared to refugiums

If you are starting a new tank, then the obvious difference is that a scrubber gives you the option of not having a fuge at all because the scrubber can go on top of, in, or behind the display. There are other uses for a sump/fuge of course, but we'll only cover the filtration.

A not-so-obvious difference is that a scrubber, if run together with a fuge with macros, will kill the macros even though the macros are much larger. This is because the scrubber thinks the macros are nuisance algae. Some people do run both together without killing the macros, but this is just because their scrubber is not strong enough, and actually the macros might even be slowing down the scrubber because the scrubber thinks it has to remove the macros, and the nutrients in the water, and the nuisance algae in the display. However, if it works for the current setup, good.

But assuming you have to decide on either a sump/fuge or a scrubber (not both)...

o Filtration with algae is proportional to photosynthesis, which is proportional to Light x Flow x Attachment. Meaning, stronger light grows more algae; stronger water flow grows more algae; and stronger attachment lets more algae grow without floating away. A scrubber is designed to maximize Light, Flow, and Attachment.

o The main problem with macros in a refugium is the self-shading that the macros do. Any part of the macro which is not directly in front of the light at any moment is not filtering. And any macro inside of a "ball" of macro (like chaeto) is self-shaded all the time. Only the surface macro that is directly in front of the light is doing any real filtering. A scrubber is designed to have all the algae in front of the light at all times. Rotating macro does not solve the problem because the time that the macro is rotated away from the light is time that the macro is not filtering. This is why it takes a much larger size of chaeto to do the same filtering as a scrubber.

o Self flow-blocking is another problem of macros in a refugium, for the same reason as light-blocking. And the thicker the "ball" of macro, the more the flow-blocking.

o Particle trapping is another result of a ball of macro. These particles need to cycle back around to feed the corals, but instead they get trapped in the macro and rot, and in doing so they block even more flow and light.

o With a scrubber, there is very little water standing in the way of the light. Also, the light is (or should be) very close to the scrubber... 4 inches (10cm) or less. The power of light varies with the inverse square of the distance, so going from 8" to 4" actually gives you 4X the power, not 2X. And the nutrient removal power of algae is proportional to the power of the light, because it's the photosynthesis that is doing the filtering.

o Rapid flow across the algae in a scrubber gives more delivery of nutrients, compared to the slow moving water in a fuge. Filtering is proportion to nutrient flow.

o The turbulence of water moving over the sections of algae in a scrubber help to remove the boundary layer of water around the algae. This boundary layer slows the transfer of metabolites in and out of the algae. There is no turbulence in a fuge (if there were, you'd have waves and bubbles).

o Scrubbers do not let food particles settle like a refugium does; most particles flow right out of the scrubber.

o Scrubbers do not (if cleaned properly) release strands into display, like chaeto does.

o Scrubbers do not go sexual, like caulerpa can.

o Scrubbers do grow lots of pods; more than was previously thought.

o Scrubber don't, obviously, provide a place for snails and crabs, etc.

However, if you already have a sump with an empty compartment, and you don't mind using all of it and putting a light over it, then maybe it's easier and cheaper to try macros than even a DIY scrubber.



Edited August 2024

[alum]

I still confuse baut my refugium tank after i installed scrubber net tank, there is not macroalgae can grow in the refugium tank they all fall out by the time, now is empty only DSB and small live rock in it,

any idea its better i uninstall the refugium tank or just leave it that way ???

[SantaMonica]

Remove macroalgae from refugium. You can leave rock and sand in the refugium.

[Floyd R Turbo]

This I do agree with. One thing to add is that flow also remove oxygen which is produced by photosynthesis, and one recently posted study showed that if the O2 is not taken away via water flow, it tends to "stop things up" and reduce photosynthesis rates (explanation greatly simplified). This would be the case especially in a large tight ball of chaeto.

[alum]

Remove macroalgae from refugium. You can leave rock and sand in the refugium.

Yup thats my opinion! probably they scrambling food between algae from ATS and macroalgae.
I made create the water flow on ATS over and over back to the screen, finaly to refugium tank then return pump. feeding times for ATS more than refugium tank.

SM : cause there is no macroalgae on my refugium tank, so that is called RDSB tank now ???
does it need light (daylight) on my refugium tank ???

[SantaMonica]

No.

[Remed]

No.

I have the same problem with this one.

@SantaMonica
You mean "no" no need light on refugium tank or "no" this not called RDSB Tank ?
needing explanation. thx.

[Ace25]

No need for light if there is nothing photosynthetic in the "refugium" anymore. A RDSB doesn't need light at all.

I never had a better functioning SPS reef than when I had this as my sump. 15G sump on a 75G tank, middle chamber STUFFED with Caulerpa (bottom completely shaded as you can see, but still green and still grew fine). To me that is like saying trees can't grow branches and leaves below the top of the tree because the top canopy blocks the light for the leaves below.. but we know that isn't true either. For 2 years before I moved to an ATS this is how I ran it, and for 2 years I never had ANY detectable phosphate readings and the macro algae just grew and grew without problems, die off, or going sexual (same with my SPS corals, I was getting 12" inches a MONTH of growth on certain acropora!). Actually, this sump is the same sump I used on a 29G tank previously before I upgraded, so the sump was actually 7+ years old before I moved it to my upgraded/new 75G tank at the time. I had many other locals come over with their own Hanna meters to test my tank and verify themselves it was always a 0.00 reading. I did use GFO as well at the time, but only 1/4 cup in a TLF reactor and only changed it once a month. Since switching to an ATS I have, since day 1, had a phosphate problem and no matter how many different ways I try and remedy the situation, I can't seem to make an ATS work anywhere close to what my old refugium use to run... but I still try because I do think the ATS is a great filtration method, but I also think it requires some other methods beyond what I used to use in the picture below because I went from using 1/4 cup of GFO a month to 1 cup of GFO a week and even at 1 cups worth, it was spent in 7 days and could never bottom out phosphates to 0.00 like I used to get, best I ever got was 0.03 when using lanthanum + phosguard and that only lasted a day before phosphates were on the rise again.

http://farm4.staticflickr.com/3059/2567998433_265ff0ca0c_o.jpg

[SantaMonica]

Since switching to an ATS I have, since day 1, had a phosphate problem

If algae were the cause of the phosphate problem, you would have had the problem with the chaeto too.

[Remed]

No need for light if there is nothing photosynthetic in the "refugium" anymore. A RDSB doesn't need light at all.


Ok I got it. thx.

[Floyd R Turbo]

He didn't say it was the cause, he said it couldn't keep the phosphates down like the previous setup.

[Ace25]

My point was on my old system, between the filtration methods I used, 50% weekly water changes, and MH+T5 combo, I had found a perfect balance in the tank to where everything was happy... at a huge monetary expense to me. It was one of many different combinations of filtration/lighting methods that have been proven successful at one point by someone. I am not saying algae was the cause of my past success or blaming it for my recent failures, I am just saying in the past I used the refugium/macro algae method along with other costly methods and I never had the negatives you speak of with using caulerpa or chaeto and had what I felt was a well balanced healthy tank.

Today I no longer have an extra $300+ a month just to spend on salt and other supplies for my tanks. This was the driving factor for me to move to an ATS and switch lighting to LEDs... but it has created a lot of changes to the tank and created lots of different issues for me to work out. The ATS has never functioned as claimed for me, but again, I still believe it is a very good filtration method that provides plenty of benefits so it will always be a part of all my tanks from now on. It has functioned as well as can logically be expected of it. I will not rely on an ATS to solve all my tanks problems anymore than I would rely on any other macro algae to solve all of them. I have stopped doing water changes, tried... and tried.. and tried many times over the past 4 years to not have to use any type of phosphate remover like I previously used (but to no avail, again, not the algaes fault) so going from 50% weekly to nothing for over a year and still have living SPS corals tells me something is working right, but I certainly wouldn't call any of my SPS corals 'healthy' at this time. I just need to find that type of balance and stability in my tank like I used to have, and do so at the smallest expense possible. I think an ATS is an integral part of that, but not the only part.

Back on topic.. scrubber vs refugium .. they do some of the same things, and they do other things different. I think it is possible to have a nice refugium along with a scrubber without issue if that is what someone wants, you just have to pick the right macro algae if you wish to use macro algae in the refugium. Mangroves and halemeda would still grow nicely in a refugium as both require very low N/P. A few mangroves and a little halimeda in a refugium will do very little in terms of helping filter the water clean, but they won't require much either. So an ATS should not negatively affect those types of plants... chaeto on the other hand, an ATS will wipe it out, and caulerpa, I would be afraid of stress of sudden lack of nutrients would lead to die off or turning sexual, both would cause major issues, so I would not use either of those macro algae in combination with a scrubber. A refugium does provide benefits that an ATS can't provide and vise versa. On at ATS, pods are bad, they eat the algae and release it into the water, but in a refugium with some rock rubble piles, they can grow and multiply and feed the tank which is a good thing. As long as you clean the screen weekly it shouldn't be a problem. On an ATS, algae grows much faster and is much easier and safer to harvest vs a refugium. There are many other pro's and cons of each method so it comes down the each person to decide how they want to run their system. If you want an ATS and refugium because of the different things they provide or the visual appeal of a nice looking refugium with maybe even a mantis shrimp in it, just pick your macro algae wisely if you want to use some. A refugium doesn't need to contain anything photosynthetic in order to be called a refugium.. by name, it is a place of refuge for things that would eat or get eaten in the display tank, things you find beneficial to the tank and want to keep somewhere safe from everyone else or have multiply. One could even have a refugium of sun corals and dendros and not have to use light if you wanted and it would provide some filtration and look stunning.

[ferdinand]

so now you use 2 filtering, Mr. Ace? ATS & refugium? does it solves the phosphate problem?

[Ace25]

Well.. yes and no.. I used to use what would be considered a full blown refugium with both caulerpa and chaeto macro algae, today I just have a bunch of live rock on the bottom of my sump and use the ATS as my algae filter. I could not use either caulerpa or chaeto macro algae with an ATS though, they wouldn't survive. The live rock in the sump area is there just for bacteria and microfauna to grow (pods, microbrittle starfish, tube worms, etc). So far my setup is still not designed well enough to lower phosphates naturally, but I am still trying to find out why and how to fix it.

[ferdinand]

Well.. yes and no.. I used to use what would be considered a full blown refugium with both caulerpa and chaeto macro algae, today I just have a bunch of live rock on the bottom of my sump and use the ATS as my algae filter. I could not use either caulerpa or chaeto macro algae with an ATS though, they wouldn't survive. The live rock in the sump area is there just for bacteria and microfauna to grow (pods, microbrittle starfish, tube worms, etc). So far my setup is still not designed well enough to lower phosphates naturally, but I am still trying to find out why and how to fix it.

i think you can try removing your LR from your system ace, if phosphate is your concern & not growing bacteria also microfauna

[Ace25]

Read these links.. http://www.advancedaquarist.com/2002/9/chemistry and http://www.nano-reef.com/forums/lofiversion/index.php/t265251.html

I don't think removing live rock on my systems is the answer to my problems. I boiled, let dry outside for 30 days, and cooked for 1 year (seeding with Dr. Tim's bacteria) to ensure it was as clean as could be so I think it is helping on my tanks more than harming them. With the rock in my display and sump combined, I am still less than 1 pound per gallon.

Anyway, that is getting off topic again, this thread is about scrubbers vs refugiums.

[ferdinand]

maybe you should read again those links, it'll tell you where phosphate source & usually run into.

scrubbers remove it but refugiums keep it. but it said in that links too that fish & corals can also deposit phosphate too, so maybe you can keep your refugiums & remove your fish & corals?

you maybe ensure your LR clean when you put it in (i'm not sure tho) but you put phosphate in by feeding & scrubbers is not like a vacuum cleaner that will suck all phosphate in the aquarium, it needs time, some phosphate will deposit to fish-corals-sands-rock & even to the aquarium & later will eventually release it again to the water.

well, its your aquarium, its your call which one you want to keep it. you can keep it all, but you need to put out your MONEY out to buy some product to vanish it.

i'm maybe not a master on aquarium & don't know your motif but i know when you don't stop the 'cause, don't mind the 'effect.

[Ace25]

Wow, sounds like you know my system better than myself. LOL. Did you take into account we are talking golf ball size pieces of rubble, in one chamber that is 18"x10", just enough rubble to cover the floor under the ATS screen.. and also the fact there are 2 Koralia 3 powerheads in that one chamber to keep everything suspended and not settle. No? Didn't realize that part? Don't be so quick to judge other peoples setups without getting a full picture.

My rock was killed, left out to dry, soaked in RO/DI water and rinsed for a week, then put in clean saltwater with Dr. Tim's bacteria and cooked for a year in a 29G tank with 3 powerheads and a skimmer without any light. I put a few small pieces of rubble from my tank to also seed the life, which it did very well as there were tons of pods and starfish on the rocks. The water tested 0/0 for several months before I used it in my tanks, so I am pretty sure it was clean.

Also, this is how my tank is setup, rock sits on drilled PVC frame which has a 1400GPH pump pushing flow upwards through the rocks to keep them clean. 20 years experience, I have learned a few things.
http://farm3.staticflickr.com/2157/2547250440_11b7bfe549.jpg http://farm8.staticflickr.com/7051/6787958416_a9b47abc79.jpg

[ferdinand]

yeah, i don't know your setups, even when you put a picture or video, i'm still not 100% sure it's yours too though. but it just like this site & all other site around the world, if we belief, use it, if not don't use it. cause we never know what other people motif.

well, back to the topic, you like to research things right? you can test your koralia absorbing capability since it can grow bacteria in there like you said, 'suspended is enough for chemicals to deposit especially when the media have the capability to absorb.

[xerophyte_nyc]

To me that is like saying trees can't grow branches and leaves below the top of the tree because the top canopy blocks the light for the leaves below.. but we know that isn't true either.

Actually, it is true. Take a closer look at trees and really any branching plant. The newer and also more active leaves are at the tips of branches. When growth is fast, the older leaves become senescent at a quicker rate. Inhibitory hormones at the meristems prevent side shoot development to enhance photosynthetic surface area.

[Ace25]

yeah, i don't know your setups, even when you put a picture or video, i'm still not 100% sure it's yours too though.

My flickr album (http://www.flickr.com/photos/39658161@N00/).. my youtube channel (http://www.youtube.com/user/ace25805).. still don't think that is my tank?


Actually, it is true. Take a closer look at trees and really any branching plant. The newer and also more active leaves are at the tips of branches. When growth is fast, the older leaves become senescent at a quicker rate. Inhibitory hormones at the meristems prevent side shoot development to enhance photosynthetic surface area.

Ok, I am taking a closer look at this 'branching plant' I found on google images, I don't see leaves dying below the top of the plant. It looks pretty uniform to me actually.

http://www.marijuanaseedbanks.com/images/marijuana_leaf_pics/images/marijuana_plant.jpg

[kerry]

You have great growth going there!!!

[tebo]

a good amount of money in there lol

[Garf]

"Found on Google Images" - yeah, right. Thanks for sharing Ace.

[Pulse]

Plants position their leaves to use sunlight as efficiently as possible.

I will admit the stuff in the image above left me a bit hazy though.

[xerophyte_nyc]

Wouldn't mind some of that action right about now, LOL!

Just walk through any forest or area of mature growth and you will see that the older branches and lower parts of plant life have leaves of a different morphology. It's not even debatable. Speak to any horticulturalist/ botanist/ ecologist if you want more details about this.

Are there examples that show otherwise? Sure. Your photo shows a plant that was likely grown indoors where the lighting regime can be modified to attain better growth. But even if that were not the case, there are plenty of fast growing plants that can grow so quick that many leaves remain on the plant. In due time, even they will have older, yellowing leaves.

Back to algae: if light is intense enough, or if the algae is illuminated from wide angles, then you can certainly get good growth where the net result could be adequate. However, it is difficult, as far as I'm concerned, to argue that photosynthesis occurs at the same rate when chlorophyll is clearly shaded by other growth.

[Pulse]

Many leaves on that plant will die of light starvation and require pruning to avoid air stagnation and powdery mildew, and I am sure it has seen pruning already. Looks a little stretchy but I am sure that will go away after it goes into flowering. Keep doing what you are doing and maybe FIM the tops a little more if you have time... Oh wait, wrong forum.

[Ace25]

LOL, seriously, not my plant.. haven't grown anything of that nature in decades.

Bottom line, plants differ, some plants do as xerophyte_nyc stated and lose their lower leaves/branches, while other plants do not. Ever seen a Christmas tree? Even the plant above, while yes, the lower leaves will slowly die off before the top leaves, that doesn't mean the bottom leaves are not useful (as I found out the hard way once but trimming the lower dying leaves off, only to cause the plant to hermi from the stress). The dying leaves, while they may not do much in the way of photosynthesis towards end of life, they do act as sort of a battery to the plant. The upper leaves do the photosynthesis and the extra energy from that can be stored into the lower leaves. If you trim off the lower leaves before they are completely dead, you trim off the excess storage capacity of the plant.... but again, different plants behave differently and human interaction can change the growth style drastically (ie. Screen of Green). Waaaaay off topic now though.

Back on topic.. I still think a scrubber = refugium in many aspects, but obviously not all. A refugium with macro algae can be just as good as a scrubber if built correctly, but I think a refugium will always take more space to accomplish the same goal in regards to using algae to filter the water.

[SantaMonica]

Update:

Scrubbers compared to refugiums

If you are starting a new tank, then the obvious difference is that a scrubber gives you the option of not having a fuge at all because the scrubber can go on top of, in, or behind the display. There are other uses for a sump/fuge of course, but we'll only cover the filtration concerns.

A not-so-obvious difference is that a scrubber, if run together with a fuge with macros, will kill the macros even though the macros are much larger. This is because the scrubber thinks the macros are nuisance algae. Some people do run both together without killing the macros, but this is just because their scrubber is not strong enough, and actually the macros might even be slowing down the scrubber because the scrubber thinks it has to remove the macros, and the nutrients in the water, and the nuisance algae in the display. However, if it works for their current setup, good.

But assuming you have to decide on either a sump/fuge or a scrubber (not both)...

o Filtration with algae is proportional photosynthesis, which is proportional to Light X Flow X Attachment. Meaning, stronger light grows more algae; stronger water flow grows more algae; and stronger attachment lets more algae grow without it floating away. A scrubber is designed to maximize Light, Flow, and Attachment.

o The main problem with macros in a refugium is the self-shading that the macros do. Any part of the macro which is not directly in front of the light at any moment is not filtering. And any macro inside of a "ball" of macro (like chaeto) is self-shaded all the time. Only the surface macro that is directly in front of the light is doing any real filtering. A scrubber is designed to have all the algae in front of the light at all times. Rotating the macro does not solve the problem because the time that the macro is rotated away from the light is time that the macro is not filtering. This is why it takes a much larger size of chaeto to do the same filtering as a scrubber.

o Self-flow-blocking is another problem of macros in a refugium, for the same reason as light-blocking. And the thicker the "ball" of macro, the worse the flow-blocking.

o Particle trapping is another result of a ball of macro. These particles need to cycle back around to feed the corals, but instead they get trapped in the macro and rot, and in doing so they block even more flow and light.

o With a scrubber, there is very little water standing in the way of the light. Also, the light is (or should be) very close to the scrubber... 4 inches (10cm) or less. The power of light varies with the inverse square of the distance, so going from 8" to 4" actually gives you 4X the power, not 2X. And the nutrient removal power of algae is proportional to the power of the light, because it's the photosynthesis that is doing the filtering.

o Rapid flow across the algae in a scrubber gives more delivery of nutrients, compared to the slow moving water in a fuge. Filtering is proportion to nutrient flow.

o The turbulence of water moving over the sections of algae in a scrubber help to remove the boundary layer of water around the algae. This boundary layer slows the transfer of metabolites in and out of the algae. There is no turbulence in a fuge (if there were, you'd have waves and bubbles).

o Scrubbers do not let food particles settle like a refugium does; most particles flow right out of the scrubber.

o Scrubbers do not (if cleaned properly) release strands into display, like chaeto does.

o Scrubbers do not go sexual, like caulerpa can.

o Scrubbers do grow lots of pods; more than was previously thought.

o Scrubber don't, obviously, provide a place for snails and crabs, etc.

However, if you already have a sump with an empty compartment, and you don't mind using all of it and putting a light over it, then maybe it's easier and cheaper to try macros than even a DIY scrubber.