so i've got at least 20 AG brews under my belt... the 6-7 brews were done intirely with distilled water. I bought 2 5 gallon plastic carboys to take to the grocery store to get water from one of those machines, i don't believe it to be reverse osmosis, but it wayyyyyyyyyy more cost effective. when I was brewing with the distilled I was avereaging mid 70s for efficency. I haven't been over 65 since the switch. I use a 10 gallon cooler with a false bottom, it empties out the side so I don't have a dip tube. I have always collected wort to my desired preboil and stopped... and I don't feel as though I leave alot behind. I fly sparge by setting the hose on top of the grain bed, and its at least a 40 min sparge. I just don't know what I'm doing wrong. my grain is milled at my LHBS where I have always gotten my grain. someone please help!!!!