# denitrate canister filter. need help with flow.



## firthy13 (Dec 16, 2007)

im having nitrate dramas.
i have had a look in to this and i want to start another canister full of either matrix or seachem denitrate to try and get a good colony of anaerobic bacteria to consume nitrates.
i know to do this, a very low flow rate is needed as to provide a 'no oxygen' environment to the centre of each of the pieces of matrix or denitrate.

my question is:
how low is low?
would a 400 litre output ehiem be to much??????????

info

malawi hap/frontosa tank. about 15-20 at an average of 9-10 cm
holey rock and black 2mm substrate.
4x2x2, 450L
ammonia-0
nitrite-0
nitrate-20-80ppm
45-50% water changes every saturday
it gets to about 80 ppm at the end of the week
only feed 3 times a week

any advice would be much appreciated


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## noddy (Nov 20, 2006)

80 ppm sounds really high. I have very heavily stocked tropheus tanks and the only time the nitrates come close to even 40 ppm is when the canister filters need cleaning out. I was told that adding another canister filter would do nothing to reduce nitrates.


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## firthy13 (Dec 16, 2007)

yeh that is true, but im not aiming for aerobic bacteria (the bacteria that converts ammonia and nitrites) whith needs oxygen rich water.
im aiming for anaerobic bacteria (bacteria which breaks down nitrates) it need low oxygen. thats the reason im using the seachem denitrate.


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## ladybugzcrunch (Jul 26, 2009)

I can not answer your question but would like to hear more about this filter media if you figure it out let me know.


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## KaiserSousay (Nov 2, 2008)

http://www.google.com/search?hl=en&source=hp&q=coil+denitrifier&aq=f&oq=&aqi=
Would suggest, do some reading...then decide if this is something you really want to try.


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## SupeDM (Jan 26, 2009)

Seachems Denitrate is a Ion Exchange resin that bonds nitrate supposedly on contact. It does not need a low oxygen environment to do its job. The system that you are trying to create is very hard to balance. You need a very low flow and very long tubing. The idea is that the bacteria that colonize the inside of the tubing at the beginning use up the ammonia then the nitrite and then the available oxygen. After this still inside the tubing the anerobic bacteria start to consume the nitrate. There is one drawback to this and that is that these bacteria produce hydrodgen sulfide that will be absorbed into the water and is quite toxic to fish. Another problem is that if the tubing is too long other types of bacteria will actually colonize and reverse the nitrogen cycle and reconvert the hydrogen sulfide into nitrogen enriched then ammonia enriched water. This system is called a coil denitrifier and it can be done correctly, however the balance is almost impossible to keep. Every time the bioload on the aquarium changes the length of the tubing would have to be adjusted. Also water changes would change amount of available nitrate therefore change the length of the tubing or the flow rate needed.


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## Toby_H (Apr 15, 2005)

Based on my readings... denitrators definitely work... but are far too delicate of a blaance for me to both with...

From my experience denitrating medias are too expensive to bother with...

From my experience, 15~20, 9~10 cm (3.5~4") bullet shaped fish should keep nitrates at 80 ppm in a 450 Liter (120 gal) tank with 50% weekly water changes...

Unless there is a lot of waste being left in the system...

Have you tried simply cleaning your filters more frequently?

A lot of people follow the theory that "canister filters don't need to be cleaned very often"... but the reality is, the trapped waste breaks down in the filter as opposed to being removed from the system... thus causing nitrates to increase unnecessarily...


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