How much water flow is enough

good day

I have a question about the proper amount of flow in a tank.

I have a 65Gl tank
Protein Skimmer powered by a MaxiJet 1200
2 canister filters with two seperate out spouts
powerhead Maxijet 900
FOWLR

The out spouts of the canisters are both in the center and each point to an adjacent cornor. The 900 is on the right side in the front and pushes water in the front of hte tank to the other side. If I put flake food in the tank it does flow from the right all the way through the front, around the cornor around the rock and through the back side of the tank. it moves slow but it almost makes is back to where it started.

Now when I say slow ( of course where the power head is it moves pretty fast) then when it turns the cornor and heads to the rear of the tank it slows down a bit. I would say the total trip takes about 45 seconds.
Please see attachment

I am not sure if this is fine or if I should add another powerhead. I guess could also change the placement around a bit

I added another PIC that shows the from of the tank with the rock work

 

It depends on what you are keeping. Fish only 10 times the volume is fine. Softies mixed and LPS 20 times is fine and SPS dominant 30+ times. You can go higher if you want just make sure no coral is in the direct path of the flow.

 

more flow with sps the better