When I first started with my reef tank, I had plans! I wanted to have enough corals where a 30% water change once/month would replenish the needed minerals. After cycling, I did a 90% water change. 1 month later, I did a 30% water change...Why did I do a water change? I'm not really sure, it was according to schedule and something I just usually do out of habit. Currently I have very few corals as I'm taking my time and letting the tank settle while trying to find a balance. DKH (10.9), Calc (450), Mag (1500) PO4 is undectable by Selifert Nitrate has been descreasing as the skimmer and algae reactor picks up. POR (.03 or less) Nitrate (5) Once I have enough Corals to deplete the (DKH, Calc, Mag), then I would consider dosing something. If your water readings are good, why do a water change? Am I missing something?