Urgently paging all the brilliant minds of this forum! My tank's nitrate levels are really high--somewhere in the range of 20-40 ppm, even after doing many water changes. I found out today it's because my tap has an equally high nitrate concentration--somewhere between 20-40 ppm. Before the nitrates in my tank were ~5-10 from all the algae growing, but with the addition of my algae cleaning crew nitrates have shot back up again. I'm now concerned for the safety of the critters in my tank (although they don't seem to mind. They just quietly sit there eating and are even visibly growing). Any ideas on how to lower nitrate concentration without doing water changes? Any advice would be greatly appreciated!!