Ok just tested paramaters today and excited to say 0 Amonia 0 Nitrites !!! Ive heard about doing a partial water change once the cycle is complete before you add any fish. I plan on doing the water change tomorrow and adding my first fish on Saturday! 72 gallon + 15 gallon sump (75% full) also 80lbs of live rock / sand so say 65 gallons +10 gallons = roughly 75-80 gallons total water volume. How many gallons should I swap out?