My Nerite consistently moves about the tank eating algae. He just moves REALLY slowly. Getting two more today to help him with the algae cleanup. I have read that they can sleep for up to 30 hours every few days. Have also read that they need to surface periodically for air but haven't seen him anywhere near the surface in the three weeks I've had him.
I have a good pH, but I worry about copper from my tap water and Flourish plant fertilizer - which I use sparingly. Not sure about the hard tap water, but there is .0001 (ppm I assume) copper in the Flourish.