I have been having a problem with m cichlids flashing as if their scales are itchy been having this issue for a long time. The water was getting low where I was after setting up another tank for my holding female I took a bit of water out if it to go in the other one.so I went and got more spring water to top it up.( I get the spring water right from the ground and I have tested the water for this spring and it's fine). I tested the water and the ammonia is 0 the nitrite is 0 and the nitrate is between 20-40ppm it's been that way for a while and I can't seem to bring it down. I have a fluval 405 cannister filter and a aquaclear 50. Plus I have a water pump to aid in circulation the tank size is 55 gallons. Filter maintenance is done at least once a month and when I do a water change I take everything out and swish the substrate to help the filter to suck up all the fish poo. We have several bottom feeders.
The substrate is only a fairly thin layer.
What could be causing my nitrate to be up?
The fish don't seem bothered aside from the flashing they are eating and. Breeding
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