29g set up for 6-7 months. Home to 9 cories, 12ish pygmy cories, 4 ADF's. Not heavily planted but reasonably so. Added some extra java fern on 17/12 bur other than that no recent changes. Sand substrate. Water change routine of 60-70% change every 8/9 days. Usually ammonia, nitrite and nitrate are all 0. Edit: also has an air stone running 24/7.
Went to do a routine test 3 days ago and had nitrite about 0.5ppm and nitrate showing about 40ppm. Did a 50% water change same day, removed a couple of decaying plant leaves and did a thorough search in case one of my fish had died but found nothing. Vacuumed all the sand. Tested again the next day and parameters were the same, so repeated the process. Tested yesterday and still the same so did another water change.
I tested my tap water yesterday (let it gas off for several hours), ammonia 0 nitrite 0 nitrate 10ppm.
The only thing I can think of is a few weeks ago I cut the filter sponge in half and put one half in my other tank to help with cycling, and added a bit of new sponge to current filter in its place. I did give the filter a good squeeze when I did my previous water change on 17/12 so am wondering if I've induced a mini crash inadvertently. None of my fish show signs of illness, all eating and swimming as normal. Is it just a case of keeping up with big daily water changes until things stabilise again? Am annoyed with myself if I did cause this as this tank has always been very stable!
Went to do a routine test 3 days ago and had nitrite about 0.5ppm and nitrate showing about 40ppm. Did a 50% water change same day, removed a couple of decaying plant leaves and did a thorough search in case one of my fish had died but found nothing. Vacuumed all the sand. Tested again the next day and parameters were the same, so repeated the process. Tested yesterday and still the same so did another water change.
I tested my tap water yesterday (let it gas off for several hours), ammonia 0 nitrite 0 nitrate 10ppm.
The only thing I can think of is a few weeks ago I cut the filter sponge in half and put one half in my other tank to help with cycling, and added a bit of new sponge to current filter in its place. I did give the filter a good squeeze when I did my previous water change on 17/12 so am wondering if I've induced a mini crash inadvertently. None of my fish show signs of illness, all eating and swimming as normal. Is it just a case of keeping up with big daily water changes until things stabilise again? Am annoyed with myself if I did cause this as this tank has always been very stable!
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