I have a 90 gallon mixed reef tank with 5 fish and a protein skimmer. When I change 15 gal/week I have no algae issues, but slow coral growth. When I change 15 gal every other week I start getting hair algae on my rocks.
What fish and do you have corals? That will help figure out the schedule.
__________________ 180g- Mostly BIG fish and some coral. ~80g Nuvo- My coral tank with "happy fish"~ 90g- FOWLR Not the not happy type of fish~ 125g- Freshwater Malawi Cichlids ~10g- Nuvo- The refugees from the Ich of '18