Setting up my 150 gallon reef tank....question re: water flow

[newreefer_59]

Have 2 Tunze 6055 powerheads at present working with the Tunze controller. Also have a Koralia powerhead by itself. So my question: How much flow is too much for an LPS coral and small fish setup? ie: would you recommend a third 6055 powerhead to be installed with the controller and should they all be placed low in each corner of the aquarium.

Many thanks.