which fish are most tolerant
I have a 35 gallon tank which I've had for a number of months now. With weekley water changes of approx. 10 gallons the nitrate level seems to hang at around 20. In this tank are two plecos, two p-sharks and two rosey barbs.
I've added other fish in the tank over the last month or so and they have all rather quickly died ( within a couple of weeks). Have I simply chosen types of fish that can't tolerart this nitrate level or am I missing something. The other fish I've had are clown loaches(2), bala sharks(2) and most recently small anglefish(3).Each time I've checked the water and found the nitrate level to be at 20 or less. Do I need to maintain a lower level to have these fish survive.