Perc,
Start with 45 bubbles per minute at 60 ml per minute. If thats not enough (tank ALK continues to drop) add 5 more bubbles per minute and allow 24 hours for the change to be effective. Do not touch the effluent setting. The effluent pH should be in the neighborhood of 6.5-6.8 and should be ~ 30dkh.
Day one: measure tank ALK and Ca
Day two: measure tank ALk, if dropping increase bubbles
Day three: measure tank ALK, if rising decrease bubbles
Day four: measure tank ALK
Continue cycle until the tank ALK does not fluctuate. Remember, reactors are designed to maintain parameters. When your numbers are solid for two or three straight days the reactor is SET. At least until you add a few clams.