Quote Originally Posted by chem geek
I thought that the conversion was 2.3 feet of water per PSI so that you would multiply PSI by 2.3 to get head loss in feet. Am I missing something?

Richard
2.31 times the filter PSI will give you only the return head loss from the filter to the pool. Head loss consists of both return and suction losses. The most accurate way to measure suction loss is with a suction guage at the pump. Unfortunately, most people do not have one nor willing to buy one so I usually skip that suggestion. So without a suction guage, a pretty good estimate for suction loss is 30% above the return head loss which results in a factor of about 3 (2.31*1.3 ~ 3). It gives an answer with a little more accuracy than 45-65 feet of head.

BTW if you do have a suction guage, then multiply inches of mercury by 1.13 to get the suction head.