New Tank.... Many Questions

[tim the toolman]

I have a 46g bowfront with a 10g sump. It has only been running for about 2 months now. I was originally running 2 Koralia2 (600gph) powerheads until one burned out. I then went to the LFS and purchased a slightly larger one (1050gph) is this going to be too much flow?? I have a few soft corals and only 4 fish. Also my canister filter is running as thereturn from my sump. The Filter is rated at 300 gph is this enough water exchange for my tank??