That could be a question for Ben to answer.... im looking at it this way....:: it's either 1/2 Cup and filter for 6-8 hrs to get the rise---OR--- 2 Cups and filter 2 hours to get the rise... I chose the latter since I was hanging at the pool the whole day anyway..... if you have the time on your hands today, (You should since it's Fathers Day , attempt the 4 cup dose atleast a few times today and see if you see a marked difference ( I know I did)...... just an fyi: it does take a bit longer to backwash.... i was/ and have been adding water throughout the process... But I think the water will be a freebie today based on the forecast...