Help! Huge nitrite & nitrate spike after stocking

[ijaco]

So on Sunday I posted wondering if my cycle was complete yet. My ammonia had been going from 5ppm to 0ppm in 24 hours, and my nitrites were down to between 0 and .25. My nitrates, however, had been stuck at around 10ppm for the whole time I was trying to fishless cycle and never really had a spike. Anyways, someone told me I should be good to go after a water change, so I did a 50% WC and went out to get some fish. I stocked about 40%, (it's a 60 gallon), but ever since I added the fish there has been a huge nitrite spike. On Monday it was 3-4 ppm and ever since then it has been off the scale! Ammonia has been steady at 0 or sometimes .25 ppm, and nitrates were around 20 ppm until tonight, they jumped up to 100 ppm. I have been doing 50% water changes daily, and have already done 2 today. I also added a lot of extra prime to detoxify the nitrites. What should I do? More water changes?

 

[Coyne]

Until you can figure out what's wrong and fix it, then water changes are your best bet for keeping your fish healthy/alive.
Good luck.


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[TomK2]

Yes, keep doing water changes.

 

[Fishfur]

From the sound of it, your filter didn't have enough BB in it to support the number of fish you added. Generally, it's best to add only a few fish at one time, and wait at least a week before adding more. It's not how many fish the tank can handle, it's how much fish waste the filter can process. BB are slow growing, so adding too many fish at one time can overwhelm the BB. Clearly you have both types, given you have nitrite and nitrate. So keep doing those water changes. Your fish are, unfortunately, at high risk, because nitrite is as bad as ammonia and nitrate levels over 50 do damage as well.

You can do multiple, total water changes, by staggering them, which is easier on the fish. Change half the water, wait a short time, change another half of the water, and you've changed 100% of it. You can do that more than once, to reduce the nitrite and nitrate levels to where they won't do harm. Keep testing, so you'll be able to tell when you have reduced the nitrite to zero or as close as you can get to zero, and nitrate to no more than 50 ppm. Ideally less than 20 ppm.

Total water changes done this way are much less stressful to fish than the levels of nitrite/nitrate you have. I've had to do it a couple of times, once when a filter failed, and I'd been away overnight. Didn't lose any fish that time at all, thankfully.

Good luck.

 

[jrc0528]

Actually doing 2 50% WCs back to back is the same as doing a 75% WC, not a 100% WC.


Lets say you have a nitrite ppm of 100 starting off.... with a 50% WC you'll reduce this to half after re-filling. You now have a nitrite level of 50ppm. Another 50% WC will cut this in half again, leaving you at 25ppm.

A 75% WC would leave you at the same 25ppm with a single WC.

 

[ScotJudd]

It's all in the maths! 10/10


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[Fishfur]

I was never any good at math . But I did say, keep testing 'til you get readings that are safe. As it happens, and entirely my fault that it did, my frog tank got a bacterial bloom. Since I have fish, snails and shrimp in there too, and it was due to accumulated food the snails didn't eat, I had to vac the gravel really well. That resulted in repeated large WCs several times in a row over about 3 days. I'd take out about 65% of the water as I sucked up the gravel, so I could rinse it before returning it to the tank.

Everybody's fine and the bloom has cleared up, and in future I'll feed less, since I overestimated how much the snails were eating.

My main point was simply that doing large, multiple changes is safer than leaving nitrite/nitrate levels too high. Keep changing until the tests show safe levels.