Nitrite Spike after water change

[polaris96]

Tank Size: 10
Age of the tank: 4 months
pH: 7.2
Ammonia: 0.25 ppm
NitrAtes: 5 ppm
nitrites: 1 ppm
GH/KH: 300+ / 53.7
Temperature: 80F
Fish in your tanks: yes
Fish:

Gourami, Barb, Cory, Tetra, Oto. 12 fish total

Question/Problem:

[polaris96]

First off, happy Independence Day, everyone!

My Sponge prefilter recently clogged. Yesterday, I performed heavy maintenance in the tank.

I drained 3 gal of water from the tank and tested the chemistry (NH[3-4] <=0.25ppm, NO2 0ppm, NO3 10ppm). I removed as many pieces of gear from the tank as possible. I let the items (rock) dry in the sun while I vacuumed the gravel. Eventually, I wound up siphoning off perhaps 4 - 4 1/2 gal of tank water.

I rinsed the sponge in the used tank water until it ran clear through the sponge. Then, I replaced the rocks and added 4 gal new water with a cocktail of 1mL Flourish Excel, 2mL Flourish Iron, 1mL flourish and about 1.5mL Prime)

I also added two new plants (red cabomba and jungle Val) and an Oto cat.

Everything LOOKS fine, but now I'm logging 1ppm of NO2 on my water test. Is this normal after a major overhaul/ waterchange? I didn't use any soap and I didn't remove any gravel or canister media, so I don't think my bacteria is whacked.

I'm concerned because I have some cherry shrimp. They seem ok, so far (fingers and toes...) but I know Nitrites are a big red flag with shrimp.

Should I be worried at this point?

Thanks a lot

[polaris96]

ok, it's a bit more than 12hr since I logged the higher Nitrite levels and now they're down to 0.5ppm. Shrimp still hanging in, too.

It does seem to be some kind of innoculation/propagation issue. Or, maybe it just takes longer for bacteria to metabolize Nitrites. I'm curious but not worried anymore.

I'll record how long it takes to settle out and post the data.

[Carl]

sorry I missed this thread (I only jumped on quickly yesterday).

Here are a few thoughts:

My first thought is the Pre-Filter was carrying more than its "fair share" of nitrifying bacteria and when even clogged the bacteria may have started to die off for lack of water flow, as well it is possible maybe an "aggressive" cleaning removed further bacteria (although I have cleaned these sponges quite aggressively and not documented this, but then I have not tested every tank after every sponge cleaning, in fact generally I have not unless a problem was suspected)

Another thought is the aldehyde contained in Flourish Excel may have interrupted the normal processes of certain nitrifying bacteria as these bacteria use aldehyde to catalyze the conversion of betaine aldehyde into glycine betaine.
This problem would likely quickly change (as would a temporary die off of some nitrifying bacteria), which may explain quickly improving numbers as to your NO2.

Carl

[polaris96]

Thanks for the suggestions. This stuff is very interesting to ponder.

I'm just about back to 0ppm on NO2 ( there is some noticable tinting in the test tube, but no shade that correlates to the chart ... I'm thinking, "just about nil." )

Interesting thought on the prefilter doing most of the heavy lifting. I've got a "way" oversized canister filter downstream of the prefilter. I guess it's a combination of annoyance and chagrin if the big dog (read that as EXPENSIVE dog) isn't picking up the slack.

Would the biomass in the canister filter starve if the prefilter was carrying most of the load?

[Carl]

Would the biomass in the canister filter starve if the pre-filter was carrying most of the load?

Generally it will still be there, just in a more dormant/less concentrated level, which if say the Pre-filter was removed, it would likely bounce back within 5-14 days (depending upon the bio load it must suddenly pick up the slack for).
This is still much better than the time to start a bio filter, as well even a weak/dormant bio filter is going to go to work immediately removing ammonia/nitrites should another bio filter be removed, even if not totally effectively in the beginning.

Carl