Jeff, Im late getting back with you and I know you left a phone message Move one station into approx 4 ft of water this fall, continue to run the system until average daily highs are apprx 40 ish for a week (could be Thanksgiving timeframe) and then shut off. If thin ice is ever a concern then leave shut down until 1st of April.If ice and snow cover with snow being the deciding factor go for 3-4 weeks without a problem as mentioned before as your fish will require smaller amounts of oxygen at that time and your supply will be high from colder temps.If you clear snow for skating your O2 will be fine as even without many plants yet you will have planktonic algae that will produce favorable levels of oxygen.If you need to blow a hole in the ice then figure the shallow diffuser will melt approx 6 inches per 24 hours at the 4 ft depth.Be sure the deeper station is shut off.