I keep my pH in my sev tank at around 6.8 with peat in the filter and some driftwood. The taps pH is 7.3 and the peat does a great job stabalizing it at 6.8.
Glad to hear that your sev's (kyleking007) are doing okay at 8. I would like to keep my tank at 7.8. My Philly city water PH tends to run on the high side.
I usually change anywhere from 60-80 gallons once a week (and never miss a water change) on my 180. I did some reading on different sites and it sounds like Sev's are pretty flexible with the PH and will easily adjust.
Usually I don't worry about the P.H. and my fish are doing great! I just feed them regulary and take good care of them. But I do check the P.H. once in a while.