I replaced my old 2.5 Hp pool pump with a pentair 3HP variable speed pump and am working on programming schedule. I've browsed through several threads and cannot find an easy way to calculate my pump flow rate. I know what I need as far as gpm but dont know how to calculate with out installing a flow meter. Is there a simple math problem that can be used. I have a 24000 gallon Pool/spa kidney pool, de filter and Raypak heater.