Mega Powerful Nitrate and Phosphate Remover - DIY! - Tropical Fish Keeping - Aquarium fish care and resources
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post #1 of 435 Old 09-20-2008, 11:20 AM Thread Starter
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Mega Powerful Nitrate and Phosphate Remover - DIY!

Mega Powerful Nitrate and Phosphate Remover - DIY!

Are you tired of green on your rocks? Do you have to clean your glass more than once a week? Well then I'm sure you've been told (or you've figured out) that your Nitrate and/or Phosphate are too high. Sure enough, if these are too high, the green starts growing. Phosphate is the important one: If you can detect any phosphate at all with a hobby test kit (like Salifert), then it's high enough to cause algae to grow. So, what can you do?

Build an algae filter screen, that's what you can do. An algae filter screen, also known as a turf algae filter, a turf scrubber, or an algae scrubber, basically filters the water clean of nitrate and phosphate so that the green on your rocks and glass goes away. It does this by "moving" the growth of the algae from the tank to a "screen" outside of the tank. The idea is that you create a better growing environment on the screen than occurs in the tank, so that the algae grows on the screen instead. It works great!

Here's what you can expect: If you build your algae filter properly, your nitrate and phosphate will be incredibly low, sometimes unmeasureable by hobby test kits, within four weeks. I use Salifert test kits, and the readings I get are "clear" (zero) for both the Nitrate and the Phosphate tests. This is what you want. If you have been trying to get this yourself, then an algae filter is for you.

Here is my Algae Filter in a 5-gallon bucket; it's the only filter I have (other than the live rock) 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 a bucket version of this filter:

My nitrate and phosphate are zero (clear on Salifert test kits), 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 only thing you need to decide on is how big your algae filter screen needs to be, and if you want it to be in your tank's hood, or in a bucket, or in your sump. The basic rule is one square inch of screen for each gallon of tank water, if the screen it lit on both sides; the screen size should be twice this if the screen is lit up on just one side. A 12 X 12 inch screen, lit both sides, = 144 square inches = 144 gal tank; a 7 X 7 inch screen lit both sides = 49 gal tank; a 6 X 6 lit both sides = 36 gal tank. Algae filters get really small as you can see. A 12 gal nano tank needs just 3 X 4 inches! This small thing can replace the skimmer, refugium, phosphate removers, nitrate removers, carbon, filtersocks, and waterchanges, IF THE PURPOSE of these devices is to reduce nitrate and phosphate. If these devices have any other purpose, then they can't be replaced. If your tank is bigger than a 75, 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 4 hours 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. I can feed the tank a lot of food, and anything not eaten by the corals or fish eventually ends up as algae on the screen.

Here are some examples of DIY algae filter screens already built, from a simple nano one:

to larger ones:

Here are some advantages of an algae filter:

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

o Can replace waterchanges, IF THE PURPOSE of the waterchange is to reduce nitrate or
phosphate or algae growth. Otherwise, it does not replace the water change.

o Grows swarms of copepods.

o Increases pH.

o Increases oxygen.

o Will NOT spread algae into the tank. It removes algae FROM the tank.

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

o Is very quiet when flowing, similar to a tabletop decorative waterfall.

o Introduces no microbubbles when adjusted.

o Removes ammonia too.

o You can even make a portable bucket! Just unplug the lights, 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 it:

First, get your screen. Any stiff material that has holes in it, like knitting backing, plastic canvas, rug canvas, gutter guard, or tank-divider will do. Try going to hardware stores, craft stores, garden stores, sewing stores, or just get one of these online (in order of preference):

Don't use window screen though. The main problem with this kind of "soft" screen will be getting it to hold its shape; it will bend and fold too much. Stiff screen is easier to make stay put, and easier to clean.

If you have a nano with a filter hatch on top of the hood, then it's super easy: Just cut a piece of screen to replace the sponge filter, and put it where the sponge filter went. Leave the hatch open, an set a strong light on it, facing down directly on the screen. This is a good bulb to get; it will be bright enough to power the screen, and to light up your nano too:

If your nano does not have a filter hatch on top of the hood, or if you have a regular tank, then here are the larger versions:

The first and main thing to consider is the flow to the screen. You need about 35 gph (gallons per hour) for every inch of width of the screen. Thus, a 2" wide screen would need 70 gph, and so on. Here is a chart:

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

1" 35
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

Note that it does not matter how tall your screen is, just how wide it is. Let's start with an overflow feed: In this case the amount of flow is pre-determined by how much is overflowing; the maximum flow you'll get to the screen will be what's going through your overflow now. This is easy to figure out by counting how many seconds it takes your overflow to fill a one-gallon jug:

60 seconds = 60 gph
30 seconds = 120 gph
15 seconds = 240 gph
10 seconds = 360 gph
8 seconds = 450 gph
5 seconds = 720 gph

Take this gph number that you end up with, and divide by 35, to get the number of inches wide the screen should be. For example, if your overflow was 240 gph, then divide this by 35 to get 6.8 (or just say 7) inches. So your screen should be 7 inches wide. How tall should it be? As tall as can fit into the area you have, and, as tall as your light bulbs will cover. But how tall it is not as important as how wide it is.

Pump feeds: Since with a pump you have control over the flow, start with the size screen you can fit into your space. If the screen will go into your sump, then measure how wide that screen will be. If the screen will go into a bucket, then measure how wide that screen will be. Take the width you get, and multiply by 35 to get the gph you need. For example if you can fit a 10 inch wide screen into your sump or bucket, then multiply 10 by 35 to get 350 gph. Thus your pumps needs to deliver 350 gph to the screen.

You can construct your setup using any method you like. The only difficult part is the "waterfall pipe", which must have a slot cut lengthwise into it where the screen goes into it. Don't cut 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. I used a Dremel moto-tool with a "cut off wheel":

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:

Lighting: This is the most important aspect of the whole thing. You must, must, have strong lighting. I'll list again the bulb I listed above:

... This the minimum you should have on BOTH sides of your screen. You can get even higher power CFL bulbs, or use multiple bulbs per side, for screens larger than 12 X 12 inches, or for tanks with higher waste loads. The higher the power of the lighting on the screen, the more nitrate and phosphate will be pulled out of the tank, and faster too.


Regardless of which version you build, the startup process is the same. First, clean the screen with running tap water (no soap) while scrubbing it with something abrasive. Then dry it off and sand it with sandpaper on both sides. Then get some algae (any type) from your system and rub it HARD into the screen on both sides, as deep and as hard as you can. Then run tap water over the screen to remove the loose algae pieces; you won't see the spores that stick... they are too small, but they are there. Don't forget this algae rubbing part... it will speed up the start of your screen by a few days. Install the screen and turn on the water.

You can leave the light on for 24 hours for the first week if you want to speed up the process; otherwise just put it on a timer for 18 hours ON, and 6 hours OFF. You will see absolutely nothing grow for the first two days. On day 3 you'll start seeing some growth, and by day 5 most of the screen should have a light brown coating. If this level of growth does not happen on your screen, your lighting is probably not strong enough, or it's not close enough to the screen. Increase the bulb power, or move it closer.

When the screen looks something like this:

...then you want to give it it's first cleaning, on ONE SIDE only. Take the screen to the sink, run tap water on it, and just push the algae off with your fingers (not fingernails):

Wait a week, and clean the other side, gently. Wait another week and clean the first side again, etc. After a while you'll have to press harder to get the tougher algae off, and after a few months you'll probably need to scrape it with something, and it may eventually get so strong that you'll need a razor blade to scrape it off. But for now, be gentle; you always want some algae to remain on the screen when you are done. NEVER clean it off completely.

Don't forget to test your Nitrate and Phosphate before you start your filter, and each day after. I use Salifert:

Post your pics of how you build it, the growth day by day, and your nitrate and phosphate readings, so we can all see how you are doing!
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post #2 of 435 Old 09-21-2008, 03:10 PM Thread Starter
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Reminder Of The Day:

What Scrubbers Consume: Algae scrubbers consume INORGANIC nitrate and phosphate. These things are what your test kits read, and what the nuisance algae on your rocks and glass require to live. What scrubbers don't consume is ORGANIC nitrate and phosphate. Organic nitrate and phosphate have another name: Food. Any and every piece of food you put into your tank has nitrate and phosphate in them, but they are organic. Scrubbers leave them in the water for the corals to eat. Skimmers do the opposite: Skimmers remove the organic nitrate and phosphate (food), and leave in the inorganic nitrate and phosphate; these inorganics are then used by the nuisance algae on your rocks and glass to grow.
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post #3 of 435 Old 09-22-2008, 10:14 PM Thread Starter
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Today's build-of-the-day is the very first solar powered screen that I've seen on any thread. Lighting will not be a problem with this one. Uses a simple pressurized pvc frame:

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post #4 of 435 Old 09-23-2008, 08:01 PM Thread Starter
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Today's N-and-P-lowering successes are both from the UR site, and both of them were a build-of-the-day that I previously posted:

"Col" says: "Test results from tonight are N=7.5 & P=0.1 I've not had test results as low as this before. The lighting on side 2 of the screen is really making a difference. Thanks SantaMonica for all your help!

"johnt" says: "Tested today and nitrate has come down from 50 to less than 25:



* = Started Scrubber

"First a big drop in Phosphate and now an equally impressive drop in Nitrate"
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post #5 of 435 Old 09-25-2008, 01:13 PM Thread Starter
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It's Time For The Santa Monica 120 Acrylic!

Ok it's time to move my screen from the ugly bucket by the sink (with hoses, wires, timers, etc) to under the tank where it can sit on the sump. The idea for this design came from all the readers who tried to install their screens over their sumps. Low profile is important for me, as it is to anyone without a fish room, so I picked 6" as the max height. That would give me room to lift out the screen and pull it out of the stand, with room to spare. And at 6" height, the pvc pipe will take up 1", leaving 5" for the screen. So the screen will be 5 X 24 = 120 sq in. This is good for a decently-stocked 90 like mine, or a lightly stocked 200 with no real nutrient problems. Here is the initial layout that I gave to the acrylic shop:

Wide screens like this are more efficient and powerful (with the same light) than tall narrow screens, but require more flow. My screen will need 24" X 35(gph/in) = 840 gph. However the same 120 sq in screen placed vertically would only need 5" X 35(gph/in) = 175 gph. The vertical placement has a disadvantage in that the water at the top gets filtered by the top of the screen, but then has to travel over the lower parts of the screen. Since it's already been filtered at the top, not much happens on the bottom part of the screen. This problem is eliminated with a horizontal screen since all the water that passes over the 5 inches of screen needs filtering.

Another good use for a low-profile screen like this would be for on-top of tank, when you want the pods to drain directly down into the display. Or, if you don't have a sump, the on-top placement would work great if you put the pump in the display.

The acrylic box came back from the acrylic shop, finished beautifully. They still have the plans, so if anyone wants the same box, call Hastings Plastics at 310-829-3449 and say you want the "aquarium algae filter screen box". The only change would be the "U" cutouts for the pipe: Tell them to make them a little larger round, and a little deeper, since the pipe was hard to push into them (and it stuck out a bit which made the lid not close all the way. ). I did a little grinding, and now it's perfect. The cost was about $100, without shipping. Here's how is arrived:

Unwrapped. Notice the bottom and ends are mirrored acrylic, with the mirror facing inwards:

The lid fits mirror-side down:

The pipe fits snug so that little light will escape. I had to grind the "U" cutouts a little bigger and deeper so the pipe would not block the lid:

The lid fit perfectly after the pipe cutouts were enlarged:

Here are the lights. They come with a combo of 10K and actinic:

I removed the bulbs, and got 6500K and 3000K from here:


I'm going to set it up with 6500K on one side and 3000K on the other. Nobody recommednds 10K for macros, except for one person: The guy at Inland Aquatics that has been growing turf screens for 10 years. So, I'll try 10K soon, but not to start. Maybe you can start with 10K on yours and let us know how it works :)

Then I placed the lights on the acrylic and marked off where the the bulbs will be shining through:

Some method has to be used to mount the lights to the sides. I'm using acrylic blocks and acrylic glue:

The light-mounting is a bit tricky, because the lights need to be removeable, yet be pressed up against the acrylic to minimize light leakage (which would be important for an above-the-tank placement in plain view). The lights are then placed in the mounts:

The overall size ended up being 6.5" high X 6" deep X 24" long:

Here's a size comparison; the inside of the stand was once filled with filtration devices, and now it's just water:

Taped and ready for spray painting:

First coat was a metallic silver, so that the inside would reflect more:

After painting with black primer, and putting lights on:

End view:

Side view:

Lid off, ready to use:

The long, low-profile pipe and screen:

Lights on:

Setting on sump:

Running, with front light removed to see flow:

So, I rubbed algae from my original bucket into the new screen, then installed the screen and turned it on. I'm starting with the flow and lights on 24 hours, in order to speed up the growth. I'll decide later if I'm going to pulse the flow, and I'll wait for the algae to grow a bit before putting the lights on a timer. Also, there is no fan, because I wanted to make it as simple as possible for folks who wanted to try it themselves. I may try a fan later, but for now let's see how it does without one. Also also, I'm leaving my original bucket running, for safety, but of course this will slow down growth on the new screen.
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post #6 of 435 Old 09-25-2008, 07:03 PM Thread Starter
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Results of the day:

jski711 on the RF site says: "Well i ditched my euro reef skimmer and have not noticed any side effects from doing so. i'm still doing water changes on a regular basis but i have increased feedings tremendously and have no adverse side effects from doing so."

keithqueef on RC says: "Update. Well i received my screen from inland (12x12) last friday. and since putting it into my system my trates have gone from red to orange to now dark yellow not quite orange, i lost my color card so i dunno numbers. the screen is dense with it."
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post #7 of 435 Old 09-26-2008, 09:01 PM
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I will have to make something like that for my saltwater. Very useful concept, and nice DIY design.

Hey, I've seen you on another forum. This exact thread was posted on the other aquarium forum I go onto, as was the thread titled "Best cube aquarium for the $" or something like that although I don't remember the name of who posted the cube thread on fishforum.
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post #8 of 435 Old 09-27-2008, 12:54 AM Thread Starter
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Glad you think it will fit into your next SW setup. And let me know if you remember where that cube aquarium link is.
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post #9 of 435 Old 09-27-2008, 11:12 AM Thread Starter
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The Power Of Light, another example:

Reader "varga" on the RS site just did a cleaning and sent in these pics; here is before the cleaning... it looks like the screen has an even coverage all across it:

But here is after:

Notice that the center area has a tougher, stiffer algae that holds on stronger because it is made up of less water and more fibers (i.e., more N and P, less H20). Now why do you think that the stronger algae formed in the middle of the screen? Here's why:

Yes, because of the lights. The screen may look evenly covered in light when you look at it, but your eyes can't tell the high power areas from the low power areas. Also, when you double the distance of the light, you would think the power of the light would be reduced to one-half; but it's actually reduced to ONE FOURTH of what it was. So when optimizing your design, you want the lights as close to the screen as possilbe, all the way across the screen.
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post #10 of 435 Old 09-28-2008, 11:17 AM Thread Starter
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Many folks asked for pics of the jski711 no-skimmer tank whose test results I already posted, so here they are along with an update he posted:

"Well first i'll start by giving you a little background of my tank. its been up for 2 years now and am running t5 lighting. in the past i have had algae issues and phosphates tested above .1 from overfeeding. (i'm trying to fatten up my clowns and hopefully get them spawning). i've also got a 15g tank plumbed into my system that has a pair of mandarins in it which i am also trying to get spawning. i had a sick mandarin and dosed my tank with Maracyn to try and save him. after dosing this for a week i was unable to turn my skimmer on because it would just overflow from the medicine. after doing numerous water changes and about a month later i still was unable to turn it back on, thats when i saw [the scrubber] thread. I also had to turn off my calcium reactor because the co2 was dropping my ph too low; the bubbles from the skimmer were really helping me keep my ph up but with my skimmer not running, it had to be turned off. thats when i decided to give [the scrubber] a try. i purchased a pre grown screen from inland and off i went. since adding the "scrubber" i have noticed a major increase in ph which allowed me to turn my calcium reactor back on and get things stable again. the reactor has only been back on for about 2 weeks now and im "re dialing" it in. my ph fluctuates between 7.8 at night and 8.0 during the day. I have over 30 different types of sps in my tank, just did a quick count, and i have noticed no ill side effects at all. i have also been overfeeding a ton, especially to my mandarins! i have also noticed that the green film of algae i would get on the glass every few days has gone. I don't even remember the last time i scraped it, although in the pics you will see it needs to be done soon cause i have a ton of coraline algae on it. So IMO this "scrubber" has done wonders for me. I have been skimmerless for over 3 months now and still do my normal water changes, sometimes i do go 2 weeks but normally every weekend i do one. the turf that was on the screen from inland is still there but it doesnt seem to be spreading but not receding either. below are some pictures from today, they were just quick shots so sorry if they are blurry but you will see the colors i've got are great and like i said earlier i have had NO ill side effects at all."

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