Hi, I'm thinking about upgrading my rio 1400 with a larger submersible pump. I'm looking for an affordable $50-$100 pump that would output 500-600gph @6ft head. Any suggestions? I was thinking a Mag 7, but it's a little low on GPH. But a Mag 9.5 would be to much for my overflow to handle. There doesn't seem to be anything in between?