Dynamictiger, has provided some good information. There is no â€œrightâ€ pressure for all pools; however, all things being equal, the lower the pressure in the filter the more efficient the flow (15 psi to 20 psi or 35- to 45-foot pressure head) is usually relatively efficient if you look at most swimming pool pump curves (assume 5- to 10-foot suction head). Therefore, you may want to consider changing to a smaller pump motor next time it needs changing (or of you want to save electrical cost now). There are a few good websites available that discuss the advantages of reducing the pump motor horsepower (HP) for more efficient pool water circulation (I will provide links in my blog noted below shortly).
More importantâ€¦You said that your filter is cracked. This could have significant safety concerns because of the potential (pressure) energy (force). At 30 psi a 24-inch diameter filter has a force of over 13,000 pounds (two Hummers) [Force = Pressure x Area â€¦ 30 psi x pi (3.14) x 12 inches x 12 inches = 13,000+ pounds]. You should probably replace the broken part or replace the filter (increasing the filter size/flow may also reduce your system pressure and increase the efficiency).