Every organism in a reef tank needs phosphate in a way or another, some beneficial bacteria will need phosphate to be able to create tissue. You won’t slow down or starve the algae from growing as organic forms of phosphate will still be available.Why would someone dose more phosphate if the gha is eating it all wouldn’t it make it grow faster?! And I’m just trying to make sure it stays away with the cuc
Some of this beneficial bacteria if allowed to grow will also compete with the algae for other essential nutrients like ammonium.
By raising phosphate in a system that is depleted in phosphate you should notice that algae will be present, just not growing as fast as before, due to a beneficial microbial competition being re established.