Thursday, January 7, 2016

Excerpts from a fish forum that were started just recently on the internet and posted 1/6/2016.

Excerpts from a fish forum that were started just recently on the internet and posted 1/6/2016.


Anoxic filter

So I thought it was time to bore you all by banging on about my pond filter

By: Dave Collins: a senior member of eXtreme Koi, the internet’s top Koi site!


Anoxic filtration: For those who are curious about this type of filter or who are even considering installing one, I thought I’d write about my experiences of running one for the last 4 and half years. What are the advantages and disadvantages of this kind of filter?

Disadvantages: I’ll start with this first because it’s much easier. The Anoxic filter is a bio filter only so although this is not strictly a disadvantage, it does require some sort of solids removal system as a first stage. Depending on how the Anoxic container is constructed then it can take up a fair bit of surface area unless you stack the baskets vertically.

Advantages: These are many but I will try and explain a few of them.

Cost: As in everything in life nothing is free BUT there is no need to spend thousands chasing the nitrogen cycle. I currently have 60 Biocenosis Clarification Baskets in a liner pond that filters the main pond. The baskets were filled with cat litter and Laterite although there are now cheaper alternatives available to Laterite. The Biocenosis Clarification Baskets litter and Laterite worked out at £19’s each so not cheap but could be reduced to about £12’s today. The Laterite has a reported life of at least 20 years and the baskets and cat litter are forever.


Water parameters: The Anoxic filter will first “eat” ammonia, so as such there is no nitrogen cycle except for the bacteria living on all pond surfaces. As there is very little ammonia then nitrite is also low and is consumed by the filter when it has finished with the ammonia. Once this is in short supply then the filter will start to consume the nitrate and phosphate leaving the water clean. The filter has no influence on KH or pH so the pond is very stable, I have been running my pond with a KH of 2dh for years with no signs of any change.


Cleaning: I have an RDF fitted so there is very little dirt that gets into the Anoxic filter. All I have is a very light covering of mulm on some of the baskets (between 1 & 2 mm thick or .039-.078 think). I last cleaned the Anoxic filter on 4th October 2013 and have no plans to clean it in the near future.


Water changes: I don’t change the water at all and haven’t done so since installing the Anoxic filter. I top up with about 200-liters of RO water a day that is used by the RDF but that is all for my 45,000 liter (11,887.74-USG) pond. The pond is crystal clear and all parameters checked on my Hanna 83203 electronic meter are low. Current temperature is 9.4°C (48.94 ͦF) and I’m still feeding 250-gms (8.8 oz. or ½ lbs.) of 36% protein food a day.


Koi: I have about 40 Koi in the pond of which 20 are over 60cms (23.622 in). They are all looking very well and I’m hoping my Chagoi which is currently at 85cms (33.46in) will pass the 1 meter mark in the next two years. The Koi are growing well but I don’t feed for quick growth so there are no growth records being broken in my pond. The Anoxic filter also consumes growth suppressant pheromones which would explain why the Koi in my overcrowded pond are still growing.



Conclusions: I wish I’d found the Anoxic filter system before I spent thousands on all sorts of fancy filter systems that only leave you with a pond full of nitrates and a very large water bill trying to eliminate them.  




Thanks for that Dave a very good read. I did a new pond build early last year and put in a small anoxic filter {didn’t have much room for a bigger one} I too get a small mulm deposit but it is interesting that you don’t clean yours out.

 I read somewhere to clean it out twice a year to be honest I haven’t touched mine yet, though I have a drain at the bottom of it so I have flushed it out quite often.

 Does it take a long time to kick in like an ordinary filter? All my readings have been good since I built the pond so maybe it is working ok




Hi John,


 No need to clean really as the drum keeps nearly everything out. For the very small particles that get through the filter acts like a settlement chamber, still used by many, the oxygen in the water renders them harmless.

 As you say, Dr. Kevin Novak recommends complete water changes and clean out in the filter every six months. I haven't felt the need to do this, the water is sparkling and the water parameters are good.

 I'd say the Anoxic filter takes about 2 weeks to start working and depending on where you're starting from can take from 6 weeks to a few months to be performant. I had Nitrates of 200mg/l so it took about 3 months to reduce it to the current level of 25mg/l 



Does it work as good throughout the winter?

 Sent from my SM-N9005 using Tapatalk



My pond is at 8°C (46.44 ͦF) this morning and I'm still feeding a little. The performance of the filter in winter slows down with the lower temperatures just like any other filter but it is still working. 



It's good to hear comments from someone who's actually running an anoxic system as I'm considering it for my next pond.


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