Nitrites giving me headaches

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Cecil B.

Cecil B.

Plecostomus
MFK Member
Dec 16, 2011
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Ligonier, Indiana
My approximately 260 gallon system was completely non-fish cycled a couple months ago, and repeated feeding of ammonia after cycling was followed quickly by zero readings for ammonia and nitrites. The tank was cycled in the upper 70's F. and was then allowed to fall to the room temp of 65 F. The addition of ammonia at that temp continued to be followed by readings of zero for both ammonia and nitrites within a short period of time.

Fast forward to dropping the temp to 53 to 55 F. to hatch trout eggs and now they are all alevins. The nitrite readings rises every day unless I add a Proline compound to neutralize the nitrites -- twice daily. Ammonia readings continue to stay at zero and nitrate readings are under 5 mg/l.

I know the lower water temps are not conducive to nitrobactors, but I'm hoping at some point they will adapt and start doing a better job. I did add some phosphoric acid on thoughts that I may be experiencing phosphate block due to the small biomass of the alevins.

My biofilter is a moving bed filter consisting of 4 cubic feet of plastic media in a 55 gallon drum aerated and moved by a membrane diffuser on the bottom.

There should be plenty of surface area for the bacteria!

Thoughts!
 
It all has to do with temperature. The temperature for optimum growth of nitrifying bacteria is between 77-86° F (25-30° C). Growth rate is decreased by 50% at 64° F (18° C). Growth rate is decreased by 75% at 46-50° F.
That is why most trout hatcheries have flow through systems.
 
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Thanks Joe. I knew that and it makes sense, but there are cold water recirculating systems that have high density trout in them. They do increase the surface area of the bacteria by using fulidized sand filters, which I was hoping I didn't have to do based on my low load. RAS or partial RAS is mandatory in some Scandanavian countries like Norway.

I could do a partial flow through, but the only place for the overflow to go is the septic tank unless I do some re-plumbing, which I may do. Even a gallon a minute really adds up over time. Maybe I'll plumb into my back wash discharge for the iron filter and install a check valve so the iron filter backwash can't back flow to tank overflow.
 
No haven't considered that. I was under the impression plants were more for nitrate removal, at least that was what I used them for in my aquaponics setup.

Interesting ammonia is not an issue. So there is some nitrification taking place. And there is plenty of surface area for the bacteria with 4 cubic feet.
 
Nitrites were at zero this morning! Granted I did a 40 percent water change yesterday afternoon, but when I did that before, I still had nitrites the next morning. I'm cautiously optimistic.

I also slowed down the tumbling of the plastic media in the moving bed tank yesterday, started feeding some swim up fry, and stopped adding nitrifying neutralizing compound. Perhaps those were factors?

And or the addition of phosporhic acid is a factor?

I guess the problem with the shotgun approach to solving a problem is you never know which solution solved the problem or if it was all of the above or some of the above. That said I'm cautiously optimistic and don't care as long as the nitrites stay at zero on the API scale!
 
Glad things worked for you, out of curiosity is this the Cecil from the Pondboss forum?
 
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