I wish I could tell you but I'm not sure. I feed minimally do 25 percent water changes and keep the algae at bay. I have no heater and have yet to test the water. My fish all look healthy and very active and my water is crystal clear no smells. I'm pretty lucky for how I started. Btw my lfs
also sold me the run it for 1 hour then add fish and your done dream lol.