Been up an running 2 weeks. I must say, this is the greatest thing ever! I have the 45MHP22 (22 gallons/day). I am currently injecting for 10 minutes every 2 hours x 4 feedings per day. The last feeding at 6pm, I run for 15 minutes. Figure I lose maybe 1-2 ppm overnight and until the 1st feeding at 10am. My pool pump starts @ 9am and feeding times are 10, 12, 2, 4, 6. Pool pump down at 7:30pm. Anytime I check the chlorine level, I am pulling a a solid 4 ppm, which is spot on. Went with the 45MHP22 so i could inject at full speed multiple times per day, that way I keep a steady chlorine level. Got the 15 gallon barrel at the local cleaners. They get laundry soap in them. Got mine for $5.00 just make sure you wash it out really well.