# Anoxic Filtration



## Sweetmule (Apr 26, 2018)

I have a 150g stocked with Africans and am thinking about starting a discus tank. I found a discus forum - "simply discus" and started reading about anoxic filtration.

First of all, a lot of those discus guys are nuts! They typically spend their whole lives doing water changes. So, in early 2018 there were various video postings by Dr. Kevin Novak (you tube) showing a filtration system using baskets of kitty litter material and laterite instead of typical bio media. There is a lot more to it, but the results seem to be significantly lower levels of nitrates, meaning less frequent water changes. The subsequent postings on that board seem to show mixed results - some people swear by it, others not so much.

After reading that board, I'm on the fence about going forward with discus, but it made me think that maybe I should think about converting over to an anoxic filtration system for my African tank as I have a hard time keeping nitrates below 25 without weekly water changes. I have a wet dry sump and recently added an Ehiem cannister to help. Has anybody tried the anoxic filtration?


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## Old Newbie (Feb 18, 2017)

I have found that weekly water changes are absolutely necessary with my African tanks; they just seem to foul up the water pretty well. Mine graze on algae all day and no matter how little I feed I have always had 20 to 30 ppm nitrate weekly, and I do 60% to 70% water changes.


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## Sweetmule (Apr 26, 2018)

Old Newbie said:


> I have found that weekly water changes are absolutely necessary with my African tanks; they just seem to foul up the water pretty well. Mine graze on algae all day and no matter how little I feed I have always had 20 to 30 ppm nitrate weekly, and I do 60% to 70% water changes.


That's probably where I am heading as well - for weekly changes, but it shouldn't have to be that way. This anoxic system has me interested - you should check out the YouTube videos by Dr. Kevin Novak. He basically says that even in a discus tank, he only does a water change once a month.


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## Old Newbie (Feb 18, 2017)

I'm not a fan of sump filters, so this would not be an option for me. I'm kind of lazy and canisters are so easy to clean, plus, as I age it is harder and harder to spend time on my knees messing around underneath aquariums.


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## BillD (May 17, 2005)

Is the "kitty litter" zeolite? Zeolite absorbs ammonia, which would have the effect of reducing nitrate. Same happens if you remove solids before they decompose. This is why I don't like cannisters; they are way too much trouble to clean, so you tend to let them go longer between changes. An AquaClear can be cleaned weekly, with the water change.


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## Old Newbie (Feb 18, 2017)

BillD said:


> Is the "kitty litter" zeolite? Zeolite absorbs ammonia, which would have the effect of reducing nitrate. Same happens if you remove solids before they decompose. This is why I don't like cannisters; they are way too much trouble to clean, so you tend to let them go longer between changes. An AquaClear can be cleaned weekly, with the water change.


According to the videos it is plain baked clay; basically the cheapest stuff you can buy.


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## BillD (May 17, 2005)

Hard to imagine the kitty litter not turning to mud, and then being distributed to the tank. Anoxic filtration can be accomplished with a plenum beneath gravel. It, however, doesn't work if you have serious diggers in the tank. As well,if you consider the nitrate level as an indicator of the level of organic wastes in the tank (most of which aren't tested for), then, lowering it in the tank gives a false indication of what the levels may be of these other compounds may be. So, when you would have normally changed water because your nitrate level told you to, you now wouldn't.
It seems whenever filtration is discussed, little is said about the role of organic solids, namely fecal matter, and assorted other rotting plant or animal matter. While urine is immediately available to the nitrifying bacteria, solids need to be broken down first. For this reason, leaving a cannister full of mung for months is no different than leaving a UGF without cleaning for the same period.


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## Sweetmule (Apr 26, 2018)

They have quite a bit of discussion about this on the "Simply Discus" forum. Here is a link http://www.forum.simplydiscus.com/. Go to the "Water Works" tab and you will find the thread for DIY Anoxic Filtration System. It has 40+ pages of comments so there is a lot to go through but it is pretty interesting.

They do discuss using plenums and Dr. Novak has a video on that as well, but it may not be practical with Africans. The kitty litter issue is discussed as well and apparently it works well as long as you get the right type.


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