Coral reef question

Hello everyone sorry for all the questions but I am new to reef keeping, I have my tank for a few months now it's a fluval edge 12 with 7 pounds of live rock recently I purchased a Duncan coral and star polyp they both opened within the hour I put them in. My question is I change 2.2 gallons every 3 days is that too often? So I do 4.4 gallons (1 box of nutri sea water) every week. Should I keep the regimen or lower it? Thanks for the advice