Urgent Too much flow??

900 ish for mixed reef about 14-1500 gph for SPS tank. (That's just a general starting point )
Don't count skimmer just flow moving inside tank.
Power heads that turn on and off are designed for it. Otherwise you'll get clicking noise as they cycle on and off.
With two running full blast at 850gph each plus return it can still work just fine but depends on the corals and rock set up. You may have a hard time with some low flow loving corals. What is your plan for corals?

 

Also sounds like normal clownfish behavior.

 

Is this the best way to run the power heads or should they both be on at the same time??

 

I'm not 100% sure I've got two little zoas that was on the rock and I think I have a couple of red rock that look a little bit like a stony tree (sps) maybe? Some easy but easy to care ones to start with as this is my s/w tank. Any surgestions?

 

I would leave them alternate.Maybe point one up and one more in the center.Should give you some good swirl when they change.As they age PH's become less powerfull.
Dirty heads are also less efficient.Sorry I originally thought you had them both running at once.Fish are used to turbulence but not 24 hours a day 7 days a week.