Right I am having a few problems with my 125g tank.
I noticed my male and female bn are showing what I believe is early stages of fin rot but they were fine before I did a
water change yesterday, I tested the water before waterchanging and
ammonia and nitrites were 0. When I noticed the small white parts on the very tips of their tail fins I did another test straight away and ammonia is up to 0.50 and nitrites 0.50 so will be doing another water change and limiting the food I fed over the next few days.
The only thing I did different was rinse one of the filters in tank water, I left the other filter alone. I put the water in through a siphon but I put more than enough dechlorinator in the tank.
As for the fin rot I have read that keeping the water pristine will help the finrot sort itself out.
Any ideas or did I do anything wrong?