All for a year I have had hob filters and now am converting to sump . I've read that for the appropriate head you multiply your tank volume by 5. However i have a 110 gallon and using the aboveentioned theory a 810 gph pump I had been looking was suitable. I saw fine print that this is however at 0 feet! I'm guessing to pump 6 feet which is about what I need I would need significant more horse power. What size gph rating will I need for 6' on a 110 gallon tank to have it turn enough water over?