500 GPH powerhead too strong for 10 gallon?

I bought a new powerhead (500 GPH Hydor Koralia)for my 10 gallon reef tank, I will be adding the corals next week. I have 2 percula clowns and 2 hermit in the tank. Is the 500 GPH powerhead too strong for my fish? because yesterday when I installed the powerhead the 2 percula clowns went to one corner and never swam from there, this morning when I saw one percula clown was hiding behind a rock and so I switched off the powerhead. Do I have to change to a low speed powerhead? or shall I leave it for a while for the fish to get used to?