# Nitrate reduction in an overstocked cichlid tank



## Chad Roehrich (Mar 21, 2016)

Hello everyone,

This is my first post here so bare with me. I have been trying to achieve nitrate reduction in my overstocked Malawi tank for quite some time now. With weekly water changes (50%), I was going from 40ppm to 80ppm. I know it is debatable whether or not this is actually too high, but I have designed a system that keeps it at or under 20 ppm...even waiting 2 weeks to do a water change. This was also while feeding 1 - 2 times per day.

I achieved this by simply growing plants (herbs + household plants) over the top of my tank using a custom built acrylic growbed. Here are some pictures: 

















Water is lifter up (via an airlift tube) to the right side of the box and drained on the left side. The box itself is filled with growit! (hydroton). The airlift is on a timer (30min on, 30 min off) to achieve a fill and drain type system. I could go on and on about the design of the system, so instead of trying to explain everything I will leave it up to any question. I can post picture and answer any question about it if anyone has any.

Thanks


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## kwang (Sep 16, 2012)

how big is the tank?


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## tanker3 (May 18, 2015)

What kind of plants do you have?


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## Biciclid (Jan 27, 2016)

When I set up my tanks I was thinking of doing something similar and may well do so, only doubt is how much light do the plants need to thrive enough to effectively mop up the nitrates. So yeah, what plants, what light, do you supplement with any ferts (obviously not nitrate based!). Very interested


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## Iggy Newcastle (May 15, 2012)

Nice.

Looks like some forms of pothos and sansiveria(sp?)


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## Chad Roehrich (Mar 21, 2016)

The tank is 60 gallons. I'm unfortunately out of town so I will post the names of plants when I return. The tank is located under 2 large windows (about 10 feet above tank) and that has been enough to keep up with the nitrates. With that being said, the plant growth has slowed down. I bought the plants (which were all located in dirt) and placed them in buckets for a month. Each day I would add another 1/4 inch of water to start getting the roots use to being very wet. During this time, they were next to a bright window and grew much faster. As my fish get bigger, I may have to add a small light over the tank.

Another thing I learned is that the roots like some dry periods. Initially, I had it set up as a continuous flow setup. Within 2 - 3 weeks of switching to flood and drain, the root system doubled! This is one nice thing about a clear growled.

Another thing I learned is that potassium becomes the limiting nutrient. This is the only fert that I add.


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## Biciclid (Jan 27, 2016)

Good to know, if I do it I will do the wet/dry cycle and use potassium bicarbonate rather than sodium, will probably be adding sodium to the water already with the sodium thiosulfide for dechlorination


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## mbargas (Apr 19, 2009)

Chad Roehrich said:


> Hello everyone,
> I achieved this by simply growing plants (herbs + household plants) over the top of my tank using a custom built acrylic growbed. Here are some pictures:


I have similar results with hornwort. I have a 70 gal tank overflowing to a 40 gal tank below which has a growlight and hornwort which grows profusely. The water is then pumped back to the main tank. I trim down the hornwort and add it to the main tank. Some of it is then eaten by the cichlids. I hardly ever do water changes and my nitrate is always below 20.


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