Aloha, installing a UV water purifier after a sediment filter and carbon filter for whole house water use. I’m getting hung up on how to size the purifier in terms of gpm. I’ve tested my current pump and it outputs 10 gpm. In the future I hope to replace it with a grundfos that puts out 22 gpm. Do I size it to the the pump output or ?? I realize that by the time the flow goes thru the filters and twists and turns it’s probably much less but I don’t know the math to figure all that out. What is a reasonable expectation for gpm for a two person household.? We live on catchment so we are very frugal with our water use but still have all the mod cons of a normal house like dishwasher and washing machine, tho low consumption to be sure. Mahalo in advance for any input!