nitrates are driving me up the wall

[mike31154]

Yow, 25-30% water change per week, that's heavy duty. I do the same percentage but only about every 16 to 21 days. Why not start monitoring nitrate levels closely at the time you would ordinarily do a water change and extend a few days to see what happens? Take it one day at a time after that and if it gets out of hand, then do the water change.

Are you running the system with a sump? You mention bottled water, is the source reliable? Might want to do a quick TDS check on your source water, although you say there is no algae in your tank.... maybe that's the problem, algae takes up nitrates quite efficiently, but of course the wrong kind is a pain.l