do I need powerheads ?

I think 600 gph ?

 

is that the rating of the pump or the rating of the overflow???

 

oh sorry I dont know rating of overflow ?

 

i used to have a pump that was rated at 782gph but after healdoss the flow rate was only 502 or 529 i cant remember

 

ok I thought it had too much movement since my new fish stayed at the top ? Any other reason he'd do that ?

 

You need more than 400 gph more flow. Try around 1000 gph more flow On your tank, I would add 3 Koralia 1's.
There could be a lot of reasons why the clown is staying near the surface. What are your params? Age of tank?

 

tanks about a month old , cycled with live rock and sand , ph is about 8.1, salinity 1.026, temp 78% ammonia 0 , nitrate 0

 

Pretty much right on. You want about 2000GPH in there. Koralia's are the way to go IMO. I would get....hmmmmmm.....three Koralia-2s. They are rated at around 600GPH. So with the 400GPH you are looking at around 2200GPH total. That's about right IMHO.

I would venture to guess you purchased yourself a true percula? Just a guess....they like to hang out at the top of the tank. False percs like the middle of the tank.