Ran a little test in my pond with 1 inch thick ice. My conclusin is a 0.5 cfm compressor might maintain a decent area of open water, but if you plan to use it to open up a hole in thick ice, the spring thaw may happen first.
What do you consider thick ice? I am using a 12V linear pump with a max 1 cfm at 3psi. I "choke" down the CFM's electronically for shallow water winter pumping.
I adjusted my pump to approximately 0.5 cfm, kind of, sort of... I taped a 30 gallon trash bag to the air line and set the pump at a level that would fill the bag in about 8 minutes figuring 7.5 gallons per cfm.
Using that setting, I could not open a hole in 1 inch ice with a membrane diffuser in 3 hours. Got frustrated and tweaked the pump in to full flow (4.5 cfm) to see what would happen and switched to another diffuser in another area of the pond. Blew a hole in less than 5 minutes in 1 to 2 inches of ice.
![[Linked Image]](http://forums.pondboss.com/ubbthreads.php?ubb=download&Number=11852&filename=I_subscribe_zps2qlyoyn2.gif)
