I have a 90 gallon with 3 green chromis. I wanted to add 2 more to make it 5 because i heard they do alot better in schools of 5 or more. They are very skittish and i heard that people that used to have 3 had the same problem and then they added 2 more and the school acted completely different. My problem is i don't want to make my bioload to much. I change 10 gallons a week for a water change and have a 20 gallon sump overflow setup. I have 95 lbs. of live rock and have about a 3 inch sandbed. For tankmates i have 2 tru perc clownfish, flame angel, purplefish, royal gramma, yellow watchman goby, algae blenny and a foxface for a total of 11 fish. Would i be ok adding 2 more chromis or no?