Tuesday, December 31, 2013

Anoxic Filtration for the more delicate cat lover Tropical Fish Hobbyist out there.


  I hope you don't mind this lengthy email.   I want to apply the anoxic filter to my 1300 gallon multi tank system Here is some background. It dumps into a 180-gallon sump run by a 3600-gallon per hour pump. Using a fluidized filter and a pond filter with kaldness media that dumps into 3 25-micron bag filters for mechanical removal of solids into the sump and recirculated.  My local water north of Orlando is hard at times getting to 250 tds.

So, because I keep South American catfish I have to soften the water with an R/O filter while closely monitoring the pH. pH is 6.4 and tds is 65-ppm  which generally be optimal for the fish I keep. The water is clear with zero ammonia and nitrite via test kit but I cant get the nitrates below 30-ppm as measured by a LaMotte test kit despite balancing the pH and hardness with an automatic water changer. The downside of the R/O is the wastewater generated [Ed: This is as much as 3-gals of wastewater to make 1-gal of R/O water.] otherwise I could pass enough water through the system to drop the nitrates lower. The Anoxic filter (AFS) is a much better way.

 My problem is that despite the above my Leiarius Pictus catfish (Common name: Sailfin catfish or Sailfin pim and can reach a whopping +24” (60cm) in size, other whys known as a ‘tank buster’ fish.) gets a slow deterioration of its dorsal fin without ragged white or reddened areas on the fin. I am assuming the nitrate level and other dissolved organics maybe impairing the fish’s immune system. Despite excellent nutrition, dissolved oxygen, water flow and space.  I am hoping the Anoxic filter can help if this is the issue. I have read your book and assoc articles but have some questions regarding the applicability to my non-pond indoor system.   

Would the build up of sediment in the filter between the boxes be an issue with proliferation of pathogenic bacteria? Can the boxes be briefly removed to clean under and around them I could do this as soon as I see any buildup. Or would enough air get inside and kill the facultative anaerobes? Most of the solids should be caught in the bags anyway.

Is the diffuser you use for the ponds your prefilter as well?

For sediment removal would it be better to have the boxes off the bottom for cleaning purposes as well as adding more surface area for diffusion?

Should the water be entering the anoxic filter be flowing up from the bottom or the top down or is this even an issue?

Are the boxes from Aquatic Eco strong enough to lay on PVC to keep it off the bottom?

What stones are best to use on top of the boxes so the ph is not effected?

Will the clay initially cloud the water when submersed?

Is there a disadvantage to using no plants with my system? From what I gather there isn't just want to clarify this. 

Thank you for your time and for making this info available,


Leiarius Pictus catfish. Photo taken from Internet. 

Hello Jeff,

Your email really wasn’t that lengthy and it gave me enough information that now I can help you without asking you more questions to give you a better answer to your questions.

When you say “boxes” I’m assuming you mean the Biocenosis Clarification Baskets (BCB’) that make up the Anoxic Filter itself. There will be some detritus and micro-settlement in-between the BCB’ but it will not be as much as you think because of your 25-micron prefilters that you’re using to clean your water before the AFS. The BCB’ themselves will not clog so that’s one thing you can check off your list of worries.

The building up of pathogenic bacteria that is associated with bacterial infections is nothing to worry about because these bacteria will not exist with proper husbandry of the filter. These bacteria that you mention exist in dirty polluted waterways or stagnated waterways that which the Anoxic Filter will become none of those scenarios unlike Bog filters or gravel filters that clog very easily and can harbor such bacteria in a short time.

Two cleanouts a year in pond use seem to do the trick for ponds and ponds are under attack by more pathogens than fish aquariums are in most cases because of animal load and outside insults. If you were worried about such then I would add a UV sterilizer to your system. In fact at 1300-gallons of multi tank set ups, I would not even hesitate about doing so.

In most cases the BCB’ will not have to be removed from the filter at all during cleanout. However, removing them is not a problem because they will stay wet inside the baskets for a long time. Atmospheric air will not impregnate the BCB’ because of the pore structure is too small. In your case using the black plastic canvas that I mention in my blog would be a more appropriate covering for the BCB’, just click on the link below for more info.

The diffuser is use so as not to blow any detritus or cat litter around the AFS itself because of the high flow rates that you can push though the filter. Conventional filters are governed by flow rate but Anoxic filters can take better flows because water is not going through the medium itself but around it. The BCB’ will just grab the ions out of the water column by magnetic electrical charge through diffusion. Diffusers really shouldn’t be playing the part of a prefilter too but some hobbyist use BioBalls as a diffusion media then they will act like a prefilter to some extent. Look at Brian Woodcock’s diffuser and you would probably use the same kind as his along with his implementation of how he built his AFS and raising the BCB’ off the bottom of the filter bed with PVC pipe.

The inlet pipe can be coming in from the bottom or top of the AFS but that would only be a preference you will have to decide on. If you click on the top link that I have provided you will see most of your answerers in Brian’s Anoxic build.

The clay or Zeolite cat clay that you use may cloud the water initially just like activated carbon does from minute particulate matter but that will be short lived once the filter gets running and it will not harm the fish. The plants are an option that you may forgo because you will not need to cosmetically hide the filter from onlookers.

If you go through my blog you will see that a few people have used BCB’ for their Aquarium setups with great success. Your water problems for your South American cats will be long behind you when your AFS is up and running and you’ll be the envy of the tropical fish forums or clubs then. Lets face facts, if the AFS can handle dirty carp that eat as much as a small domestic cat, just think what it will do for you keeping your Nitrates down and water parameters good too. Read about Yogas’s last pond letter on low TDS, KH and GH:

I think your Leiarius Pictus will love those water conditions with less cost to you in the long run. That’s why I say the Anoxic filter is Eco-friendly because it can actually save hobbyist water instead of wasting it down the drain.

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