Thursday both diffusers had open holes. Last night it was -8°F and relatively calm. Today there was clear ice where the windmill diffuser is, and I could see a very large air bubble under the ice at 11:00 a.m. It still hadn't "popped" by 2:30 p.m. We are having steady 20 mph winds now, with gusts to 40. Temps are in the upper teens. I'll see tomorrow if it opened up.
Scott how about shooting a hole into your bubble? The shotgun pellets or bullet shouldn't penetrate far enough into the water to do any damage to the diffuser.
