If any one can answer this I would appreciate the help. I read somewhere that anything under 40ppm was o.k., but then I read that ideally you want it at around 5ppm or you will get huge amounts of algae. I had an algae problem at first but now with sae's in the tank that is under control. Just don't know if i am getting bent out of shape because my nitrates go up sometimes to 20ppm, do a water change and they go back to between 5 and 10ppm. Help