Stan, 1bps for a 4ft tank enough ah? I reduce my PH SOLELY with C02. With my 2.5ft tank I'm running at about 2.5bps with my KH4.

Tuckz, like overdrive said, you have a HOB filter which creates surface agitation and gasses off your C02. If you're not willing to change your filter (canisters are expensive) try increasing your water level as close as possible to the return of your HOB.