Trying to understand flow in my tank...

[SCreeferGuy]

I have a DSA 135 (48 X 24 X 27) with 2 Tunze 6095's (one on each end) and 2 Tunze 6055's (one on each side in back). I have just started adding frags over the last month, and the SPS (Duncan, frogspawn, chalice) are doing great. My montipora frags are also doing well.

Two days ago I added some SPS frags (orange pavona, stylopora, and a couple acropora). They are currently on a frag rack on the front of the tank acclimating. Ultimately I would love to have a SPS dominant tank.

My question is, after reading a lot, I'm still not sure what "high" flow is... It seems intuitive that feeling significant current on my hand if I move it in front of the frags then this is too much? I would think this would = "blasting them". I've noticed that the polpys retract with this kind of flow and come out best early in the morning when I only have 1 powerhead up.

I have both 6095 powerheads pointed toward the center of the tank, placed about halfway up on each end. Their current just hits the rocks at this point. Is it better to point them at the glass so they are aimed at each other more directly? Should they be moved higher on the sides and aimed down?

I have a feeling this is something I will just have to experiment with, but since are a lot of 4 foot rectangular tanks out there it seems like someone would have some helpful suggestions...?

Lastly, I could add a wavemaker (like the Tunze 6208) - but would this be overkill with 4 powerheads already? Or should I replace a back powerhead with the wavemaker..? Do wavemakers make that much differnece..?

Thanks in advance for any help!

[gone fishin]

I would say given your PH you would most likely fall into the high flow capable category. Unfortunately trial and error is the best way. There are many variables tank size, PH placement and the aquascape to name a few. Observing your corals to see how they respond to the flow in a given place is the best way. Good luck.