Haven't been on for a while. But just saw this post and thought I would give my (tested) and what works for me. I have the 1/4 hp Gast 0523 pump set up in my unattached garage, trenched 2 lines in one trench to ponds edge, note(wish I had done 3 one for shallow water during winter only to keep water open) 3/4 0r 5/8 (not sure) black poly to pond edge then ran 5/8 inch weighted hoses to a each 9 inch vertex disfusser for each line spaced about 70 feet apart in deepest part of pond. I hand poured 2--- 3 ft diameter 2 inch thick slabs to set them on while pond was empty. installed on a timer that runs from 9pm to 9 am everyday. Never have had a fish kill. Start up in spring when surface water temp hits between 50- 55 and shut down in fall at 50-55 surface water temp only run in winter long enough to blow 10ft hole if I get ice cover (approx. 15 minutes) don't want to chill water. I am no expert by any means, but got all my help from the Pond boss guys and this is what has worked great for me. Probably can get for 800- grand if you check around. Wish I had found this site before I dug pond back in 2002, redug it right 2012 bought pump in 2004 and never a problem with it. I'll post pics if I can figure it out. Good Luck your at the right place for ponds.