I think unless you are adding calcium and other stuff back to your water your not benefiting from that RO water...what is your TAP water readings? I use nothing but TAP water that sits out 24hrs....7.8 from tap, after 24hrs its 7.45 my water in my tank is 7.8 with coral rocks keeping it stable. Do you notice a lot of flashing when you water change? IF SO your changing to much water at once and its the PH fluctuation that causes that......not good.


Peace