Helical Algae Scrubber

[amwassil]

Concept:
While researching commercial algae production for food, bio-fuel and waste treatment I discovered that many designs grow algae in tubes. These are generally clear acrylic tubes of various diameters and lengths exposed either to direct sunlight or purpose-designed artificial lights. As aquarists, we all know that nuisance algae grows in clear vinyl and PVC tubing even when light is less than ideal. So why not grow algae purposely in tubing exposed to optimum light to try to duplicate the commercial designs?

Most of us don’t have space to set up a large array of straight acrylic tubes. So I thought maybe a coil of clear tubing contained in a bucket with an LED array in the center directed through the surrounding coil of tubing would duplicate the conditions. This tubing/light array could then be plumbed to a primary filter or directly to the aquarium tank.

Build:

22’ of 3/4” ID clear PVC tubing coiled inside a 5 gallon plastic bucket. Unions attach to both the input and output so the bucket can be disconnected from the rest of the filtration system. In my case, that is an MBBR in a 10 gallon Brute garbage can. If you haven’t already done so, you can see both of my MBBR filters here:

http://algaescrubber.net/forums/showthread.php?3368-Moving-Bed-amp-Algae-Scrubber-combo-filter

You can google “MBBR” to find out more about them if interested. They were developed for small aquarium use by the guys at Tyne Valley Aquatics, who seem to have rebranded themselves as Filter Pro, specializing in filter media:

http://filterpro.co.uk/

I bought 25' of 3/4" clear PVC tubing and prior to doing anything else with it, I pushed a Dremel 3/4" wire brush through it 12 times to roughen the surface. After each of the last 6 pass-throughs the brush had an attached ring of plastic fluff, so I conclude this was successful. I then determined that only 22 of the 25' of tubing was usable and cut it. A 3/4” ID tube of 22’ length has an inner surface area of 622 sq in. With my 80 gallon fish tank, this gives me 7 3/4 sq in per gallon of water, which seems adequate with a large margin of error based on the Scrubber Quick Guideline and assuming it’s basically a horizontal scrubber: http://algaescrubber.net/forums/showthread.php?65-ALGAE-SCRUBBER-FAQ

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I attached 1” ID PVC 60º elbows with male adapters to the ends of the tubing to connect to the input and output lines. The male adapters are 3/4” ID and they fit very nicely into the slip ends of the elbows. On the inside, I glued 1” ID tubing over the male threads with PVC cement. The 3/4” tubing slides into the 1” tubing, and is secured by cable ties. I put hard plastic tubes from a sponge filter drop tube into the 3/4” tubing ends so I could tighten the cable ties without deforming the tube. Note: this photo was made prior to final finish of the connections, so it shows the temporary stainless clamps and tape. The outside threads attach to 3/4" unions.

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I built an array of 6 LED panels supplied by ExpressionsLTD, using the base plates of 2 plastic humming bird feeders I purchased from Walmart to support them.

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Here’s a view of the tubing and LEDs mounted in the middle of the bucket with a threaded rod through the bottom of the bucket to the top of the LED support. When this photo was made the unions were only screwed on loosely so I could remove the tubing.

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My original plan was to paint the inside of the bucket gloss white and put a layer of aluminum foil between the tubing and the bucket walls to reflect light. Unfortunately, the paint scraped very easily and the foil was impossible to position without crumpling a lot. So I discarded this bucket and assembled everything in a new bucket in which I lined the inside with white bristol board.

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The scrubber is powered by a Sedra KSP-2000 water pump with an airline blowing directly into the pump intake port. All the commercial designs I examined injected pure CO2 into the water to enhance algae growth. I don’t have a CO2 system and did not want to add to the initial costs of this experimental unit buying one. So I opted to blow plain air into the system instead. The pump sits on the bottom of the Brute. The plumbing:

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Here’s a photo of air bubbles traveling through the tube. The flow is counter clockwise from top to bottom. The flow is sufficient to push the air all the way to the bottom and out the outflow port.

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Here’s the unit in action. It has been operating since Jan01/16::6:00pm.

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I welcome any questions and/or comments.

Now to see if the unit will grow algae, if so whether or not it's sufficient to reduce nitrate and phosphate in the fish tank, of which there are an abundance.

Water params as of Jan03/16:
1. pH: 7.0
2. Ammonia (NH3): 0.0
3. Nitrite (NO2): 0.0
4. Nitrate (NO3): 40+
5. Phosphate (PO4): 10.0

[SantaMonica]

Will be nice to see how it does. Correct you do not want to use CO2 even if you have it.

[amwassil]

Day 4

For the past couple of days the tube has been getting less and less transparent. If you look at photo 11 of my initial post, you can see very clearly that the tube is completely transparent. Not so now, it looks cloudy, although I can't see anything specific. Could be microscopic air bubbles stuck in the roughed inner surface. Something to watch for the next few days through my 3" viewing port. Lights are on 24 hours and I will leave them on for at least a few more days to see how it goes.

I bought a 3/4" ball valve to use as a flow control if it begins to look like the flow through the tube is too fast for the algae to grab on. I also bought a genuine J-tube to replace the return plumbing. I'll be installing that in a day or two.

[SantaMonica]

Some materials will haze up with the light.

[amwassil]

Some materials will haze up with the light.

Thanks, it's clear PVC tubing. As noted in my original post, I ran a Dremel wire brush though the tube a dozen times. Not surprised something microscopic might end up in those micro-grooves. Hopefully, some will be algae spores. :)

Curious: do you think stopping the waterflow and air for a day or two so the water just sits in the tube would help algae get established?

[SantaMonica]

Not at all.

[amwassil]

Day 6 (Jan07/16)

Algae has started to grow in the tubing! It starts as a small spot and then slowly grows a tail. Through my viewport I can see two fairly well developed filaments waving around in the flow (one is about an inch long and about 1/8" thick already, the other about 1/2" long and about 1/16" thick), a much smaller filament (1/8-1/4" long single strand) and two or three more spots. Quite interesting. I've been watching these off and on yesterday and today.

Jan08 output filter sock:

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This is starting to get exciting! :eek:

[SantaMonica]

Fresh or salt?

[amwassil]

Fresh.

[SantaMonica]

It will readily grow in there then.

[amwassil]

Weekly update Jan09/16

1. pH: 7.2
2. Ammonia (NH3): 0.0
3. Nitrite (NO2): 0.0
4. Nitrate (NO3): 40+
5. Phosphate (PO4): 5.0++

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[amwassil]

Weekly update Jan15/16

1. pH: 7.4
2. Ammonia (NH3): 0.0
3. Nitrite (NO2): 0.0
4. Nitrate (NO3): 40+
5. Phosphate (PO4): 5.0

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Note that phosphate is down! I cleaned the filter sock after making the above photo. So future weekly reports will show only the amount of algae sloughed off during 7 days. Algae is colonizing the tube quite nicely. I discovered that I can control the water flow by adjusting the airflow. So I put a flow control valve in the airline. My hope is that waterflow will keep the tube open enough to prevent clogging. If/when required, I can 'blow out' algae to clear the tube a little by cutting off the air completely and letting the full water flow remove loose algae strands. It remains to be seen if that will actually work or not.

[SantaMonica]

With FW it should not clog; it will just let go and fill your net.

[amwassil]

I didn't mention the following yet, but I'll do so now. On Jan03 I turned off the Marineland C360 attached to this tank. My intention was to leave it connected until I was satisfied the MBBR was maintaining ammonia and nitrite at zero, then pull it out. However, as soon as I turned it off it started to leak at the head seal. So I had to disconnect the hoses and pull the canister out of the cabinet. The next day (Jan04) there was detectable ammonia and nitrite.

The C360 had leaked at the head seal previously when pulled for cleaning and I had 'fixed' it by adding a single layer of electrical tape to the hard plastic edge that seats onto the rubber ring. One of my peeves is the tendency of canister filters to leak due to the inside pressure. I did not want to tinker with the C360 again, so I just moved it out, pulled the hoses and set it aside. So ready or not the tank was 100% on the MBBR.

Jan04: I dosed the tank with a couple capsful of Seachem Prime. Instructions say 1 capful per 50 gallons and this is an 80 gallon tank with about 70 gallons in the tank and 10 gallons in the MBBR. So I figured 2 capsful were sufficient. I continued to dose the same amount every second day (48 hours).

Jan05: I added 5 capsful of Seachem Stability in the hopes of increasing the overall bacterial count. I also added about half a liter of Hel-x media from the turtle tank MBBR. I continued adding Stability for the next several days (5 capsful daily) until I used up a new 250ml bottle of it. I ordered 5 liters of Hel-x from http://filterpro.co.uk/ .

Jan07: Both ammonia and nitrite were back down to zero. And phosphate started to drop!

Jan13: Used the last of the Stability. Note, I had added some of it to both the turtle and frog tanks, so not the entire 250ml went into the fish tank.

Jan14: Reduced the Prime dose to 1 capful every 48 hours. I didn't want to risk stressing the fish by just stopping the Prime, so decided to taper off for several days.

Jan16: The Hel-x arrived a few days ago and I added a liter of it to the MBBR along with a tablespoon of the included bacterial gel balls. Today I am going to add another liter to this tank and the remaining 3 liters to the turtle MBBR and divvy up the bacterial gel balls between the two.

[amwassil]

Jan17/16

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The sock is 12" long. The solid mass of algae at the bottom of the sock is about 1.5" high by about 1/2" thick, full width. This has come out of the scrubber in 2 days! I have also noticed that a lot of very fine algae particulate is coming out of the scrubber and passing right through the sock. It exits the MBBR and ends up in the prefilter. I now have to clean my prefilter every day to keep it from clogging.

So... I have an idea for a more efficient filter on the scrubber output which I think will reduce the algae particulate from getting back to the aquarium. In the meantime, I have a Seachem 'The Bag' which has a 180 micron pore size. The filter socks I'm using now have a 400 micron pore size, so the Seachem bag should stop at least some of the fine particulate.

The tube is colonizing heavily. There is a layer of algae growing pretty much over the entire interior surface. There are a few small bare spots, but overall the algae seems to be holding on well. Here are views through my viewing port, with and without the LEDs on:

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So first part of the experiment is a success. The algae colonized the tube and is growing. Now to watch how it affects tank nutrients over the next few weeks and determine whether or not it is relatively self-cleaning, aside from the output filter.

So far so good! :rolleyes:

[amwassil]

Jan20/16

Today I incorporated a Seachem 'The Bag', 180 micron pore size, as the return filter from the scrubber. Here are photos of the components prior to and after assembly:

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The black parts are 2" ABS, a section of standard pipe with a slot cut out and a standard coupling. The white tube is a piece of 2" PVC schedule 40 pipe (thin walled) that fits perfectly into the 2" ABS pipe section. I cut a slot in the ABS pipe section so I could compress it enough to get the nylon bag into the coupling. The PVC pipe then applies pressure to tighten the ABS pipe against the bag and the outer ABS coupling. The bag is thus held snugly and won't slip out under the force of water flowing into it. The C-clamp holds the filter assembly in place against the Brute side. At the moment, the clamp is not needed since the J-tube in use has a built-in plastic spring tang to hold it solidly against the Brute side. When I replace this particular J-tube, the C-clamp will be needed to hold it in place.

When I pulled the sock to replace it with the new filter assembly, it had about the same amount of algae in it as I removed on Jan17.

[amwassil]

Weekly update Jan22/16

1. pH: 7.0
2. Ammonia (NH3): 0.0
3. Nitrite (NO2): 0.50
4. Nitrate (NO3): 40+
5. Phosphate (PO4): > 2.0

After making the above tests, I immediately added 3 capsful of Prime, waited about half an hour and remeasured Nitrite (NO2) at: 0.25. I don't know if Prime is masking the rest of it or if my original test was falsely high. I'll keep track of it daily.

On Jan16, I added 2 liters of new Hel-x to the MBBR, plus 3 tablespoons of bacterial gel balls. I am hoping the nitrite spike is the result of the new Hel-x media colonizing with the bacteria that converts ammonia to nitrite, but not yet the bacteria that converts nitrite to nitrate. If so, then I expect nitrite to go down again during the next couple of weeks. I will continue using Prime to detoxify it until it gets back to zero again. If it does not start going back down within a couple of weeks, I guess I'll have to figure out what else might be causing it.

I did not post a photo of the algae in the filter today because the new filter has only been online for a couple of days and the trapped algae wasn't very spectacular. It seems to be working OK, but I'll find out tomorrow when I clean the prefilter if the 180 micron screen is doing a better job of trapping the fines.

[amwassil]

Jan23/16

Not sure what to make of it, but nitrite is back to 0.0 today. I really doubt that the new Hel-x media got colonized completely overnight, so possibly yesterday's tests were false for some reason. Or maybe the algae in the scrubber got a sudden craving for nitrite! I'll keep testing for a few days to see what happens.

[amwassil]

Weekly update Jan29/16

1. pH: 7.2
2. Ammonia (NH3): 0.0
3. Nitrite (NO2): 0.0
4. Nitrate (NO3): 40+
5. Phosphate (PO4): > 2.0

Not much happened this week probably due to the airline feeding into the water pump getting disconnected. So there were 3, maybe 4 days of no air. I wasn't paying much attention to it but finally noticed that there wasn't much/any air flowing through the scrubber and discovered the problem. What I noticed first was the algae seemed to be thinning in the tubing, which I thought rather odd. Anyway, I got it reconnected yesterday, air is flowing through and algae seems to be growing back again. So this coming week should be better.

A lot of fine algae particles are still getting through the 180 micron 'The Bag' sock. It does not seem to be causing any problems really other than collecting in the prefilter. It's not causing any water cloudiness so I may just let it go for awhile, although I am thinking about a more elaborate filter. I wonder if the fine algae particles in the water do anything beneficial? Anyone know about that? Thanks.

[SantaMonica]

I've also forgotten to connect up the air.

The algae particles probably won't help. You are not trying to grow anything that would eat them.

[amwassil]

Monthly update Feb01/16

1. pH: 7.4
2. Ammonia (NH3): 0.0
3. Nitrite (NO2): 0.25
4. Nitrate (NO3): 40+
5. Phosphate (PO4): 2.0

First monthly report! For some reason Nitrites spiked a little. I added 2 capsful of Prime to neutralize that. Phosphate is down over the month from 10 at the beginning of Jan. So that's a good sign. I expect it will go to zero before the end of the month. Algae has regrown nicely throughout the tube since I restarted the airflow. It's very thick again.

Jan30: I started a single 'large' pouch of Algone in a small, hang-on overflow type filter. This stuff is supposed to reduce nitrates. From my experience so far, I don't expect the algae scrubber alone to bring down nitrates within a reasonable timeframe (months rather than years). So I'll see if the Algone helps.

[amwassil]

Weekly update Feb05/16

1. pH: 7.4
2. Ammonia (NH3): 0.0
3. Nitrite (NO2): 0.0
4. Nitrate (NO3): 40+
5. Phosphate (PO4): 2.0

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The left photo was made on Feb03 and the right photo today. The sock was totally clogged on Feb03, so I made a photo prior to cleaning it. I do not know how long it had been clogged before I happened to look at it and notice water going over the top. So now, I check the sock every day. Even though the pores of the sock were clogged all the way to the top, there was not all that much algae in the bottom of the sock, maybe about 3/4" - 1". I don't know if that was the total that had accumulated or if algae had run over the top once the pores clogged all the way up. I cleaned the prefilter the day before and today and it was heavily saturated with algal dust both days, although I recall it was a bit more clogged three days ago than today. That suggests that the sock had been clogged for at least a day or two before I noticed and algae was flowing out over the top during that time. The algae dust that gets into the main tank is still not causing any noticeable cloudiness, so I guess the prefilter is sucking it out of the water pretty efficiently.

[amwassil]

Weekly update Feb12/16

1. pH: 7.4
2. Ammonia (NH3): 0.0
3. Nitrite (NO2): 0.0
4. Nitrate (NO3): 40+
5. Phosphate (PO4): 2.0

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[amwassil]

Monthly update Mar08/16

1. pH: 7.2
2. Ammonia (NH3): 0.0
3. Nitrite (NO2): 0.0
4. Nitrate (NO3): 40+
5. Phosphate (PO4): 1.0

Dropping down to monthly reports. Not enough happening to warrant weekly any more.

[amwassil]

Monthly update Apr01/16

1. pH: 7.0
2. Ammonia (NH3): 0.0
3. Nitrite (NO2): 0.0
4. Nitrate (NO3): 40.0+
5. Phosphate (PO4): 2.0+

The scrubber seems to be growing lots of algae and I added a small filter with Algone. But still no sign of any drop in nitrates and phosphate went back up. Maybe last month's phosphate was a fluke.

I'm going to start 'cleaning' the scrubber tubes more frequently by turning off the air and lights for a couple of days each week. Maybe that will force the algae to grow more vigorously. I don't get a lot of algae in the filter sock, although, a lot seems to get pulverized and passes through into the aquarium. So I'm wondering if the algae in the tubes doesn't grow all that well and only falls off when the air and lights are out.

[SantaMonica]

Turning off lights or air will kill a lot of the algae in the tubes. Probably not the best way to clean them.

[amwassil]

Turning off lights or air will kill a lot of the algae in the tubes. Probably not the best way to clean them.

I don't know what else to do to stimulate the growth. Running a brush through the tube is impossible; I tried, and it only goes a few feet before it binds up. I bought some API Nitra Zorb today and I'm going to use it to try to knock down the nitrates in the tank. If that's successful I will then see if the scrubber can maintain the low level or not. So two or three months or so of continued testing.

If the helical idea doesn't work, I have another idea for a 'modular' scrubber to function as the sole filtration. I'm beginning to think of 'bio-filtration' (i.e. nitrification) as just a high yield nitrate system. I'm going to do some testing of concept with the 15 gallon gourami tank. There are currently 2 1.2x drops and a sponge filter in there. I'm going to pull the sponge since it's the source of all the nitrates. If I get all the nitrates out, so the algae can't eat that, I will see if the two drops can keep the ammonia low enough to be safe.

[amwassil]

I am starting to wonder whether the helical scrubber is actually doing much of anything. Although there is a fair amount of green, presumable algae, dust in the main pre filter, I collect very little algae in the outflow filter sock. What I suspect is happening is that algae has colonized the tubing and is just sort of sitting there, neither sloughing off nor growing much at all.

I have removed a set of two LED light units from the helical scrubber and used them to build a big upflow HOG scrubber. I will start another thread to describe this new scrubber.

[amwassil]

May23/16

I am officially taking the helical scrubber offline. It's had almost 4 months now and the scrubber does not seem to grow much algae. There is algae in the tubes, but it's patchy and has been for several weeks now. So whatever has grown in the tubes appears to have just reached a kind of 'steady state' low level of growth. So I must conclude that it's not very effective. There is quite a bit of fine algae 'dust' caught in the pre filter every day. That can only be coming from the helical scrubber sock where the water flow must be pulverizing it through the mesh. That means it's not totally dead, just not very good at doing what I need it to do. I think the new UAS will grow more algae faster, so I'm scavenging the LEDs off the helical scrubber to build UASs: one more big one for the big fish tank and a smaller one for the gourami tank.

I should also mention here that the Nitrate level in the fish tank has actually gone down. I'll report on that over in my NitraZorb test thread.

[SantaMonica]

This design was made a while back and patented, but they never marketing it. Maybe they had the same trouble.

[amwassil]

Interesting. There seems to be a lot less algae 'dust' on the pre filter today, so I conclude that I was right to suspect the helical scrubber was dumping it into the water. Fortunately, that will mean less frequent cleaning of the fabric and sponge. It had got almost to the point of daily cleaning, which is a bit much.