Mega-Powerful Nitrate and Phosphate Remover Replaces Skimmer, Refugium, part 1-4

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Part 4 of 4

Any "grow light" used for plants should work. And the brighter, the better. If your screen size is very small, you may be able to use a light on just one side, and a mirror on the other.

Now put the pump and tubes in your tank/sump, clip the fan on the bucket, and go! You should start seeing algae in a few days! If you already have a skimmer or refugium or other devices, just add your new turf algae filter to your system. Then you can start reducing or turning off your other filters one by one. Just be sure to test for nitrate and phosphate daily as you do this. And do post your pics and stories!

The screen usually starts out with green hair algae first, and after a few months you should start seeing a dark brown/red stiff "turf" algae. The only maintenance is to remove ("harvest") some of the algae from ONE HALF of the screen once a week. Thus, since this screen has two sides, you just do one side per week. If you choose a one-sided sump screen (described below), then you just do half of that side per week. Remember you will see mostly a green hair algae to start with (for several weeks), but eventually you will have a stiff reddish brown turf (a few months). So when you do your weekly harvesting, remove/washoff the green algae first, and leave behind any reddish turf you find. Do this by "scrubbing" or "massaging" the green algae in your sink with tap water running over it, kind of like you are washing your hair. This will remove the green, but will leave the brown/red. And even when you are removing the green, don't clean it completely... try to leave a little bit so it can start growning again quickly. Do this for several months until reddish/brown turf fills the screen, like this:

At this point you can start removing the turf itself along with the green hair; do this by "scraping" it using a razor blade or metal scraper (it is much harder to remove this reddish/brown stuff). Don't scrape it super clean though; leave some roughness behind. And remove less of the turf, and less often, than you have been the green. The red/brown turf is a much stronger filter, and it grows much slower, so you want to keep a lot of it on your screen to do most of the filtering. But it can only do it's job if the light is not blocked out by the green, so always keep the green "rubbed" or "massaged" off of the red/brown.

Always throw the scraped material away; this is the nitrate and phosphate that was taken out of your tank! You never want to put it back (or feed it) to your tank. Also, always use tap water (fresh water) to do your screen washings/scrapings, because the fresh water will kill any pods living in the turf (pods eat turf.) Lastly, to make the turf grow even faster, you can try adding Kent's Iron liquid to the tank water, per instructions.

Here are some $ options to make your turf work better:

o Put a timer on the lights: 18 hours on, 6 hours off. This will give the algae time to
"rest". Make sure it's on during the overnight when your tank lights are off.

o Use metal halide or sodium plant-grow lights; the more light the better, and the lower
their K rating (more "red") the better. Don't melt the plastic parts though.

o Put a wavemaker (on-off-on) timer on the pump to simulate waves; gives the algae more
air between the flows. I used the JBJ Ocean Pulse Duo timer ($50 new), and set it to 30
seconds. (note: this timer has a quirk: if you cut the power to it, then restore it, it
keeps the pump "on"; to get the on-off-on function working again, you have to turn the
dial to the left and back again.)

o Hang the bucket up high, so it can drain right into your display; all the live pods that
grow in the screen will flow down right to your corals. Remember this height will reduce
your pump flow, so choose your pump accordingly.

o Get a screen with red/brown turf algae already growing on it; will save you months of waiting
for the high-power red/brown turf to grow (it will start working instantly; this is what I
did). Call Mike at Inland Aquatics 812-232-9000, and get a turf screen overnighted to you.
They charge $10 for 16 square inches (4 X 4), so just tell him how many square inches you
need. Then you'll need to pay for overnight delivery to your location. Already have your
bucket operating, though, so you can throw the screen right in; it will need lights and flow
immediately upon arrival.

How to build the in-sump versions:

There are three sump versions to choose from. Version 1 is the easiest to build, but less powerful because the screen is only one-sided, and also because the water is not flowing evenly across the screen. But it's the only one where you can keep your bio balls (maybe for a heavy fish waste load) if you want to. And it's so easy to build that you may as well start with it if you already have a sump with a "media tray" in it:

First, size the screen to fit in the media tray in your sump. Now, based on what kind of lid you have on the media tray (where the overflow pipe connects), you will need to drill out that lid so air and light can get through. If that lid is clear, then you need just enough holes to get air in. But if the lid is not clear and it blocks light, you'll need to make many large holes or cutouts in it (or replace it with a clear one). And that's it for version 1! Just clip on the light and fan, and you are done. Use the same light as the bucket version above.

In-Sump Version 2:

This version allows a more even flow of air/water over the screen, since the overflow is not pouring directly on the screen like version 1. Version 2 needs the same openings on the lid as version 1, however, and of course the bio balls must be removed. The media tray will spread out the water from the overflow into an even-drip across the screen. The screen must still get air, however, so if the media tray does not allow enough air from the fan to pass through, you'll need to enlarge the holes in it.

In-Sump Version 3:

This version is basically the same as the bucket version described above, but it is contained in the sump. You need to cut away most or all of the lid and the media tray, and connect the overflow directly to a waterflow pipe (shown in the pic as a green "spraybar"). This version is also the only one that allows lighting from both sides of the screen, thus doubling the filtering power of it, as well as being more open for light and air.

The advantages of a sump version are:

o No extra space needed outside of tank.
o Can be set up in a limited fashion in a few minutes, as a test.
o Can make use of the wasted space once used by bio balls.
o No pump required!


o Since it is fed from overflow, you get no option to use a timer on the pump for on-off-on
wave action.
o Pods have to flow through your return pump to get to your tank.
o If the top of your sump is opaque (blocks light), it will need to be drilled or cut open
for air.
o It is not portable.

That's it! I hope some folks give it a try! Do post your pics and stories...
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Mega-Powerful Nitrate and Phosphate Remover Replaces Skimmer, Refugium, part 1 of 4

Part 3 of 4

Now you need to make the "waterfall pipe". It's exactly like what is used on those tabletop decorative waterfountains. I used a 1" ID pvc pipe (1-1/4 OD), from any hardware store. Before you cut it, install a cap (I used 1") on one end, using teflon tape to seal it:

You need to water-test the cap too, so fill the pipe up with water (cap at bottom) and check for leaks. If no leaks, empty water and dry off. Now set the pipe down on the top of the bucket and position it so that the cap touches the bucket:

Measure 1.5" from the outside of the bucket, mark the pipe, and cut it there:

Now get another hose adapter that matches your vinyl tubing size: adapter/0

Find a "reducer" that takes the size of the pipe down to the size of this hose adapter; I used a 1" to 3/4":

Attach the reducer to the other end of the pipe using teflon tape:

And screw the hose adapter onto the reducer, using Teflon tape:

Screen: The screen pictured here is a plastic tank divider (get the biggest one, and cut it down), but almost any stiff and porous material will do, as long as it stands up straight: divider/0

Even if you don't use a tank-divider, get one anyway so you can use the plastic edges that come with it to hold your screen in place. Window screen (non-metal only) can work, but would not stand up by itself too well, so you'd still need to build a non-metal frame to hold it. What also works good is knitting backing material. Whatever screen material you use, get enough to make THREE full screens, because you are probably going to mess up at least one the first time.

Size the screen so it fits in your bucket, using the dimensions you get from measuring the bucket; make the screen a little bigger than you think you need so you can trim it to fit:

Cut the screen to shape, and attatch the edges (that come with the tank-divider); your screen should now have a "V" shape, and about a half inch of the screen should stick out past the edges on the top:

Now lay the bucket down sideways, and lay the screen on the bucket so that the extra half-inch of screen sticks out past the top of the bucket, and the edges are even with the top:

Now mark the bottom of the edges about 1/4" up from the bottom of the bucket. And mark the bottom of the screen about 1" from the bottom:

Cut the screen bottom, and edge bottoms, and clip on the small edging that comes with the tank-divider:

Cut 1/2" off the top corners of the screen, and use sandpaper to make the screen rough on both sides (turf will stick to it better).

Next is the waterfall pipe "slot" that the screen goes in. Start by measuring how wide the top of the screen is, then mark that length plus 1/4" more on both side so the screen can fit in easily. Then mark the slot to be 1/8" wide:

Don't mark the slot too wide; just start with 1/8", and you can increase it later if you need to, based on the flow you get. Now comes the only difficult part of the whole project, cutting the slot in the pipe. You may need to get help to make the cut; anyone who builds models, or does woodworking, should be able to help. I used a Dremel moto-tool with a "cut off wheel":

It might be a good idea to make TWO pipes in case you or your helper mess up the cut on one of them. Now install the pipe onto the screen/bucket by tilting the pipe and starting at one side, then lowering the pipe over the rest. You may have to wiggle the screen in some places to get it to fit in:

Now figure some way to hold the hold the pipe to the top of the bucket. I used office clips on both sides of the pipe, with a paperclip across them, but you can use anything that works for you (string, tape, clamps, etc.) You will be taking the pipe on and off several times as you make adjustments, so don't attach it permanently.

Now time to test! Connect up the pump to the pipe with vinyl tubing, and use sink or tub filled with tap water:

Run the pump and make sure the water covers most of the screen. Here's a video of the first time running water through this one:

Adjust your pump output and screen placement in the pipe so that water flows out smoothly without spraying (the water should only flow down the screen; it should not shoot out sideways.) If water sprays sideways (hitting the side of the bucket), then the slot is too narrow, or the flow is too much. First try reducing flow with a ball valve, a smaller pump, or a clamp on the hose. If you can't do these, then widen the slot with a Dremel or file.

If, on the other hand, all the water flows out of the first part of the pipe and does not make it to the end of the pipe, then the slot is too wide or the flow is too little. You can fix this by adding more pump flow, or by adding extra layers of screen (making the screen thicker) at the part where it goes into the pipe. Last resort is to just make another pipe with a slot that is more narrow. If you just can't get total screen coverage with water, it's ok since those areas will be filled in once the algae grows in other places.

If all looks well, then clip on the lights: My example bucket uses two 23 Watt, 5100K compact fluorescents "full-spectrum" (125W output equivalent):

Next, look for part 4 of 4 here:


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Mega-Powerful Nitrate and Phosphate Remover Replaces Skimmer, Refugium, part 1 of 4

Part 2 of 4

o Is the very smallest size for the amount of nitrate and phosphate removing it does.

o High removal of nitrate and phosphate, low removal of foods (the OPPOSITE of a skimmer).

o Can entirely replace refugium, skimmer, DSB, carbon, phosban, polyfilters, etc. (although
you can certainly keep these items around if you want.)

o Grows copepods and amphipods that will drain right down into your display (if the bucket
is hung above the display).

o Bucket is easily hung above display with its handle, and is lightweight since it holds no water.

o Removes both nitrate and phosphate, unlike rock/sand (which removes only nitrate), or
phosban (which removes only phosphate).

o Bucket version is extremely easy to build, using just a bucket and pvc pipe.

o Version 1 of the in-sump version is so simple, it's just a few minutes to build.

o There are no moving parts at all.

o Provides cooling of water, using increased evaporation, especially with a fan.

o Does not form bacteria or slime like vodka dosing does.

o Increases pH.

o Increases oxygen.

o Does not release strands into the display like chaeto algae does.

o Will not spread into the display like caulerpa can.

o Gets strong light penetration into the turf, since there is no water standing over it.

o Easy to clean; just lift the screen up and "scrape" (i.e., "harvest") it.

o Traps no waste like a refugium or DSB does; waste flows right past the screen.

o There is no odor from the turf (only a slight ocean smell when scraping it).

o There is nothing to break or clog.

o Bucket version is very quiet when flowing, similar to a tabletop decorative waterfall.

o Introduces no microbubbles when adjusted.

o Will not start growing turf in display tank.

o No filtersocks (or any mechanical filter) needed, since you want all the food in the
water to continue circulating until eaten by the corals.

o You do not have to turn a skimmer off when feeding, because a skimmer is not running in
the first place.

o Removes ammonia too, which takes some load off your rock and sand.

o You can even make the bucket portable! Just unplug the lights and fan, lift up the pump
out of the tank water, and go put it in your next tank (or your friend's tank). Don't let
the screen dry out though.

o Works in saltwater or freshwater.

How to build the bucket version: First, choose your pump size (or just try what pump you have; it won't hurt). For my example, about 350 gallons per hour was needed. Here is a guide based on the width of the screen (it does not matter how tall the screen is)...

Screen Width-----Gallons Per Hour (GPH)

2" 70
3" 105
4" 140
5" 175
6" 210
7" 245
8" 280
9" 315
10" 350
11" 385
12" 420
13" 455
14" 490
15" 525
16" 560
17" 595
18" 630
19" 665
20" 700

Also make your pump decision based on how high up the water has to be pumped; my bucket is on the counter by the sink, so the water has to come up 4 feet (4 foot head) from the sump to get to the top of the bucket. So I needed a pump rated anywhere from 500 to 700 gph to begin with, in order to have 350 gph at the bucket. Just make sure you have an adjustable pump output so you can reduce the flow to avoid over-spraying. Get some vinyl tubing of the size that will connect to the nozzle on the pump, and make it long enough to get to where you are going to set the bucket. Make note of the ID (inside diameter) of the vinyl tubing, and don't confuse that with the outside diameter. The ID needed to match my pump was 3/4"

Now, choose a WHITE bucket size that will hold your screen (you should have already figured out what screen size you need). I used a regular 5 gallon salt bucket. (I'd also recommend you get two buckets in case you mess up the first one.) If you don't know how to do plumbing/pipes/tubes/etc, here's how.

First, get one of these hose adapters: your hardware store, or online like here:

...Choose the adapter size that matches the ID of your vinyl tubing (I used 3/4"). Next, get a bulkhead that matches the size of that adapter: your hardware store, or online like here:

...The "size" of the bulkhead is what you want to match to the adapter, and you want a "FIPT SLIP" (female international pipe thread). I used the 3/4" FIPT SLIP 1-3/8" 1", which means: the water passage area is 3/4", female threads, an outside diameter of 1-3/8", and 1" long. So make note of the outside diameter (D) of your bulkhead: this is the size of the hole you need to drill in the bucket. Also, get TWO of these bulkheads, and use the extra rubber washer that comes with the second one, so you'll have two washers together.

Now get a "hole saw" like this: your hardware store, or online like here:

...and pick the size that matches the OD of the diameter of the bulkhead. (Note that these example holesaws also need an "arbor", which is the piece that goes into the drill; they are listed at the bottom of the same page). Take the nut from the bulkhead, and slide it down the inside wall of the bucket so that it just touches the bottom. If the bottom has a curved corner, don't let the nut on the curved part; you want the nut to only be on the flat part of the wall:

Now get a black marker pen and circle the INSIDE of the nut, nice and dark, so you can see the circle from the outside of the bucket:

Hold the bucket so light goes inside it, and you should see the circle from the outside; Now mark the circle on the outside:

Now use the hole saw to drill the hole in the bottom of the bucket. Clean up the hole very good so that there are not any scraps of plastic left over that will stop the rubber washers from sealing:

Insert and screw together the bulkhead, using TWO rubber washers on the outside (take one from a second bulkhead):

Screw in the hose adapter, using teflon tape to make sure it seals watertight:

Now put your finger over the hole to seal it, and fill the bucket up with tap water to make sure the bulkhead does not leak.

Next, look for part 3 of 4 here:


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Mega-Powerful Nitrate and Phosphate Remover Replaces Skimmer, Refugium, part 1 of 4

Mega-Powerful Nitrate and Phosphate Remover Replaces Skimmer, Refugium, and Everything Else

Part 1 of 4

If anybody has not yet hooked up their refugium or skimmer, or was just looking get rid of these things, then you might want to try one of these mega-powerful filters that I built. You build it with stuff laying around, and it can take as little as a few minutes, or up to a day. It will replace (or keep you from needing) a skimmer, refugium, phosphate removers, nitrate removers, carbon, filtersocks, and possibly even waterchanges.

It's called a Turf Algae Filter, and it works in salt or freshwater. It's smaller than most pieces of reef equipment (yet it's more powerful), and it can be put into a bucket or your sump. It's most powerful feature is that it leaves food particles in the tank so the corals can feed, yet it removes nitrates and phosphates, most of the time down to zero. This is the OPPOSITE of what a skimmer does; a skimmer removes food particles (so corals starve) and then leaves the nitrate and phosphate in the water so you have to use other methods to get the nitrate and phosphate out. And how about all that gunk that your skimmer pulls out? Well, half of it is food that you just fed, and your corals wanted to eat it. What about the other half, the waste? Well, that's food too!

Here is my Turf Algae Filter in a 5-gallon bucket; it's the only filter I have of any kind on my 100 gallon reef:

Here is the filter in operation with the lights on:

Here is my tank:


And here are the only things you need to build it:

My nitrate and phosphate are zero, and the only thing in my sump is: Water. I removed the skimmer, carbon, phosban, polyfilter(s), and filtersock; I don't use ozone, vodka, zeo or anything else. I'm feeding massive amounts too; enough that if I had my previous filtering setup, I'd have to clean the glass twice a day, and everything in the tank would be covered in green or brown algae. Amazing.

The process of using turf algae to filter aquariums has been around for decades, but the contraptions were huge and expensive, and for some reason nobody thought to make a simple one in a bucket or sump. So here is one you can make in a few minutes, or a day, depending on which one you choose. It's simple enough (and basically free) that you should try one on your system even if you have no intention of eliminating your skimmer/refugium, etc.

The principal is very simple: You have a screen; light is aimed at the screen, and tank water is streamed over the screen. What happens is that a type of algae called "turf" starts growing on the screen (it feels very similar to artificial turf on football fields), and this turf eats ALMOST ALL the nitrate and phosphate in the water flowing over it. However, the turf does NOT eat the food/pods/plankton in the water, so this food will stay in the water for the corals to eat. This is the OPPOSITE of a skimmer, which takes out the food/pods/plankton (so corals starve), but leaves in the nitrate and phosphate that you have to then get out using other means. What about fish waste that skimmers normally pull out? Well that's food too, for somebody. Only after waste decomposes completely into nitrate and phosphate is it no longer "food", and at that point the turf algae zaps it! After all, what do you think the green algae on your rocks and glass are eating? Food? No. Nitrate and phosphate!

You might ask why you have not heard of turf algae filters before. Well turf algae is actually used quite a bit in commercial/industrial areas to clean lakes and rivers, but the units that were built for aquariums were just too big (as big as the tank itself) and expensive ($3,000+). So they never caught on. But all they do is move water across a screen, and have a light. So putting the turf in a bucket or your sump works just fine.

The only thing you need to decide is how big your screen needs to be, and if you want it to be in a bucket or your sump. The basic rule is one square inch of screen for each gallon of tank water. A 5 gallon bucket (like a salt bucket) can hold a screen about 12 X 12 inches = 144 square inches = 144 gal tank; a 2 gallon bucket can hold about 7 X 7 inches = 49 gal tank; a one gallon bucket about 6 X 6 = 36 gal tank. Turf filters get really small as you can see. A 12 gal nano tank needs just 3 X 4 inches in a tupperware container! This small thing replaces the skimmer, refugium, phosphate removers, nitrate removers, carbon, filtersocks, and possibly even waterchanges (if the purpose of the waterchanges is to reduce nitrate and phosphate.) If your tank is bigger than a 144, then just start with a 5 gallon bucket size and see how it goes. You can always add a second one, or build a bigger one later.

My example bucket version takes about a day to build. Water goes in the pvc pipe at the top, flows down over the screen, then drains out the bottom. That's it! Oh, and it has clip-on lights and a fan. I can feed the tank as much food as I want, and anything not eaten by the corals or fish eventually ends up as turf algae on the screen.

Here are the sump versions (putting turf in the sump was thought of by RC user "biomekanic")...

Good: Takes a few minutes to build:

Better: Takes about three hours to build:

Best: Takes about a day to build:

The advantages of the sump version are:

o No extra space needed.
o Version 1 can be set up in a few minutes.
o Can make use of the wasted space once used by bio balls.
o Is fed directly from the overflow, thus eliminating the pump entirely.


o Pods produced by the turf have to flow through your return pump to get you your tank.
o If the top of your sump is closed, it may need to be drilled or cut open for air/light.

Further down, I'll show how to build the bucket version since I made it myself (and have pics), then I'll show you drawings of how you'd do the in-sump versions (since I don't have pics). The bucket version is overall the most powerful, flexible, and even portable. The in-sump version (especially version 1) is easiest to build, but about half as powerful, and a little harder to access once installed. But for now, here's how a turf algae filter (bucket version) compares to other filtering options:

o Will wipe out most algae growth in the display, since nitrate and phosphate will be LOW.

o Allows you to feed very high amounts without causing nuisance algae growth in the tank.

o Will finally allow coralline to grow, since the phosphate will be too low stop it.

o Does not skim out coralline spores like a skimmer does.

o Can replace waterchanges, if the purpose of the waterchange is to reduce nitrate or
phosphate or algae growth.

o Has the highest nitrate and phosphate removing power of any macro algae (because of
the high air and light levels it gets).

o Is very quick to respond to excess nitrate and phosphate spikes (the turf "screen" always
stays the same size after it is trimmed); much quicker than refugiums/macros which have
smaller surface areas after they are trimmed.

Next, look for part 2 of 4 here:


AC Members
Jan 14, 2006
Sorry these are in reverse order. I combined them into one thread instead of having 4 threads, one for each part. However, it adds them in the order that they were posted in.
Since santamonica added each thread in reverse order, they are now in reverse order here.


Global Moderator
Staff member
Feb 18, 2002
Raleigh, NC would have made sense to have put them in correct order. It's harder to read this way.


AC Members
Jan 14, 2006
I originally posted them so part 1 would be first, then 2, 3, 4. To do this you have to post 4 first, then 3, then 2, then 1 as the "newest" one.
but that would have just gotten messed up anyways as soon as someone posted in one.


AC Members
Ok here are the results of the 5 gal nano test. First, here is the tank, which has 3 pounds LR, a SSB, along with a purple lobster, a starfish, and a clown:

The tank has been on an office worker's desk (his first tank), with no water changes for about four months. The last change was done only to get nitrate down (a result of overfeeding of course), in order to keep the animals happy. Phosphate was not a concern since there were no corals, and thus there was no phosphate removal system in place.

As you can see, the light and most of the hood were removed, as was the little sponge filter. The remaining part of the hood has a compartment for the sponge filter, which is 2 X 3 inches, and it has a little built in pump to move water across this compartment. I started out by taking some tank-divider material and cutting it to a tight fit into the compartment:

Then I sanded it very rough on the top, and I "seeded" it by taking some green hair algea and rubbing the algae HARD into the sanded side. Then I pushed the screen into the sponge filter compartment:

The screen is only 6 square inches, single sided, and thus not enough for this tank according to the rule of thumb of one square inch per gallon (double sided), or two square inches per gallon (single sided). Thus for this 5 gal tank single-sided I should have 10 square inches instead of 6, but of course for simplicity I just used the compartment size.

Since we had already removed the original tank light, we were going to just use the light for the screen as the new tank light too. So I just took one of the same bulbs that I used in the bucket, a 23 Watt, 5100K compact fluorescents "full-spectrum" (125W output equivalent):

...and set it directly on the plastic hood, which put it only a half inch from the flowing water:

Thankfully these CFL's run very cool, and you can put your hand right on them without burning. Of course if you try this light placement yourself, you'd want to test it carefully so that you don't melt anything, and won't knock the bulb over. I thought that the light might heat up the water, but it does not seem to. The light is on an 18-hour-on timer, and provides the tank itself with much more light than the original hood light did.

Results: Here are the measurements (Salifert) and pics taken over a period of days:

day 0..........*............*...............not measured
day 1........(50)........( .5 )
day 2..........*............*...............not measured
day 3..........*............*...............not measured
day 4..........*............*...............not measured
day 5........(50)........( .5 )
day 6........(25)........( .25 )
day 7........(15)........( .13 ).........screen full
day 8........(15)........(1.0)...........screen full
day 9........(10)........(1.0)...........whole screen cleaned (mistake)
day 10......(10)........(1.0)...........growing back
day 11......(8.0).......(1.0)...........growing back more
day 12......(8.0).......(1.0)...........half cleaned
day 13......(8.0).......( .5 )
day 14......(5.0).......( .25 ).........other half cleaned
day 15......(8.0).......( .13 )
day 16......(3.0).......( .13 ).........other half cleaned; housing cleaned
day 17......( 2.5 ).....( .05 )
day 18......( .5 ).......( .05 )
day 19......( .2 ).......( .05 ).........other half cleaned (not much there)
day 20......(0)..........( .015 ) growing back over brown

Day 2:

Hi Res:

Day 3:

Hi Res:

Day 7:

Hi Res:

Day 9, before complete cleaning:

Hi Res:

Day 9, After complete cleaning (mistake)

Hi Res:

Day 12, half cleaned:

Hi Res:

Day 16:

Hi Res:

Day 17:

Hi Res:

Day 18:

Hi Res:

Day 19, in tank:

Hi Res:

Day 19, removed:

Hi Res:

Day 19, after cleaning top half:

Hi Res:

You'll see on day 7 that the screen filled up. However I had never seen it full before, so I did not know what "full" looked like. So I left it to see how full it would get. Day 8 the screen looked the same, but there was a big increase in P, and I surmised that the screen had filled up and some strands of algae were shadowing others, causing the others to detach and flow into the tank and die (not enough light in the tank to survive). So I waited one more day to be sure (day 9), and sure enough the P was still very high.

So on Day 9 I cleaned (mistakenly) the whole screen, whereas I should have only cleaned half. Thus, I had no filtering, and it took a few day to fill in again. By day 14, nitrate and phosphate were at reasonable levels, and I was doing half-screen cleanings properly. By day 18 the nitrate and phosphate were bottoming out and staying constant, and nitrate eventually got to zero at day 20.

So the things learned:

1) A small screen size, even one sided, can do a tremendous job of filtering. (Phosphate from .5 to .015, and Nitrate from 50 to 0, in three weeks).

2) It can do this filtering with a constant flow of water (no pulsing), although a timer on the little pump would be easy to add and try out.

3) It can do this filtering with regular green algae; it has not had time to form true red/brown turf, although it was starting to feel like some was growing.

4) It all can be done in the nano's hood, with a standard light, for free.

Ok, now it's seriously time for you nano folks to try this!