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Thread: IT WORKS! Full Nitrogen cycle filter setup for reduced frequency of water changes

  1. #1
    Registered Member Milaz's Avatar
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    Mar 2019

    Default IT WORKS! Full Nitrogen cycle filter setup for reduced frequency of water changes

    This may be my second controversial post but let me state upfront, that I am not suggesting at all that frequent water changes are not needed.

    The ultimate objective is best water quality - but I would like to share herewith my experience with full nitrogen cycle filter setup - my humble opinion a very good alternative to frequent water changes.

    It might interest someone else too - who likes to keep discus - king of aquarium fish, but is afraid to do so due to high frequency of water changes needed - not always possible to do with regular out of town week or longer business trips as I have to do.

    One of key reasons for high frequency of water changes needed it is to reduce tank water pollution by nitrification end product - oxidation of toxic ammonia to less toxic nitrite and end product - yet less toxic nitrate - discus is very sensitive to any water pollution and does not tolerate any higher nitrate build up in the tank water. Traditional way to get rid of nitrate - and working very well - it is high frequency of large water changes diluting nitrates by polluted water replacement with fresh one.

    Full Nitrogen cycle filter setup does the complete cycle - nitrification by oxidizing ammonia to nitrite than further to nitrate by utilizing most of the oxygen in the water passing through the filter - but with use of specific denitrification media with a lot of internal pores / channels of specific size, where anaerobic conditions exist so colonies of good anaerobic bacteria settle there and as there is none oxygen left in the water by the time it passes inside pores of such denitrification media, they need to utilize oxygen from nitrate molecules in the water for their oxygen needs end product being inert nitrogen gas escaping from aquarium water into atmosphere eventually.

    So with full nitrogen cycle filter setup there is no nitrates buildup requiring frequent water changes to be diluted bellow harmful level.

    Rule of thumb is, that full nitrogen cycle filtration requires about 1 kg of denitrifying Biohome Ultimate media to process 100 L of aquarium water with normal stocking density however increasing to 1,5 up to 2 kg of the same media needed to clean up 100 L of water in heavily populated tanks or tanks with messy meat eaters like piranhas. More details about full nitrogen cycle filter setup for FX 5 / 6 can be found here - Richard aka Pond Guru has done a lot of videos in his video series "Pimp my filter" - many various filter types covered.

    So for my 887 L or 234 gal tank I use one FX5 and one FX6 with combined 10 kg of Biohome Ultimate denitrifying media - capable to treat up to 1000 L or 264 gal tank - plus I also run third filter (just because I had it from previous tank) - Eheim Profesional 2226 in traditional setup with Eheim Pro substrate - total combined real flow of 5.000 L/h or 22 gal per minute.

    There is yet another option to clean water in full nitrogen cycle called Anoxic filtration invented by Dr. Kevin Novak PhD - more about it here and also popularized by Syd Mitchel aka Manky Sanke here - based on this I have done my own version of unplanted anoxic filter for my 24.000 L koi pond couple years ago - more info here -

    As anoxic filter would require rather large sump tank for my 887 L or 234 gal discus tank I do not have room for, I am using the same principle of full nitrogen cycle in my two high flow Fluval FX5 and FX6 filters giving me the high water circulation I need to turn over my whole tank volume via filters every 10 to 15 minutes for fastest waste / pollution removal.

    My full nitrogen cycle filter setup allows me to extend water changes up to once per three weeks - changing 40% of tank water - not that it would be needed to remove any nitrates - these are kept very low by denitrification - but water change is needed also to replenish minerals content in the tank water to keep it healthy and in top quality.

    In my setup - if I am at home, I still do 30% water change once per week to replenish minerals sooner - very next day my Echinodorus plants thank me by new vigorous growth - but if out of town I know, that no harm can be done to my discus for up to three weeks. In March I have brought in 12 juvenile discus 6-7 cm - never needed to treat for any disease (so far - knocking on wood) - all 12 well and alive - eight growing up to 15 cm size, formed three couples - each tried to breed in my community tank during last three weeks - all three pairs laid eggs but eventually have eaten them up - to me signs of their health and happiness

    Couple pictures of first full nitrogen cycle filter cleanup - 9/9 or six months since starting it up on 5/3 :

    FX5 Filter opened after six months in operation:
    20190909_top basket prior cleaning.jpg

    Middle basket prior cleaning - Biohome Ultimate media looks like new and very clean - the same also in top basket when fine filter pad removed.
    20190909_middle basket prior cleaning.jpg

    Lowest basket prior cleaning:
    20190909_lowest basket prior cleaning.jpg

    Cleaned up basket ready to go back to work:
    20190909_cleaned lowest media basket.jpg

    Complete filter prior return to service - note, that in the top basket I use extra Biohome Ultimate media in two mesh bags for increased denitrifying performance instead of coarse and medium foams.
    20190910_cleaned up full.jpg

    Just food for thoughts - example of setup of full nitrogen cycle filtration enabling me to extend intervals between water changes up to three weeks while keeping my discus healthy an happy.....
    20190906_group in center edit.jpg

    Anyone else having similar good experience with full nitrogen cycle filter setup?
    Attached Images Attached Images
    Last edited by Milaz; 09-11-2019 at 04:42 PM.

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