I guess if no-one can answer the only way to find out for sure is to measure the flow from the pump? Maybe I am overthinking? Is too much flow through the sump from the return pump a bad thing? If I have 70 gallons total water volume and I am running at 100% minus head pressure etc say I ended up with 1000 GPH that would be 14 times turnover on my system from just the return pump...is that bad? My Nero's are set for random at 30 percent max during the day and min 10% which would give me roughly 45X turnover in the display at max speed. I understand sump flow from the return is generally kept between 3 to 5 times. I don't have coral or fish yet so can't gage flow really so going by numbers to set thingsThen what is the purpose of the calibration? From the description it seems like you calibrate the max flow so that if you vary the pump settings you would never exceed the max speed you calibrated for. Ecotech makes it sound like a failsafe to keep from overwhelming your plumbing,. Therefore if I set my max flow that my plumbing is capable of handling at 65%, then the new 100% would actually be 65% of the pumps flow capability....but maybe I am not understanding the reason for calibrating??