ewest,good question. I have not seen DW do this under the ice, Keep in mind it seems we have less and less ice all the time. Most Ohio ponds are full going into winter. Trees are defoliated which allows for more wind action, Drain tubes are usually horizontal vs bottom draw which allows for a vaccum effect under the ice when over flow takes place, Mine drain all winter. If DW did rise under the ice (I would suspect some does) it may be sucked out.Moving water (with aeration) on an ice covered pond would be greatly reduced as the flow out from the wave action would be stopped(restricted) by the ice. A lot of gallons would be turning (3000 GPM @ 12 ft with 1 cfm is common)but for the most part in an reduced area. This is where the super cooling comes into play. If wave action wanted and warmer bottom temps desired a diffuser should be suspended 3 ft below the surface so it would stay constant with any rise or fall of water level.but in a small pond of 1 acre of less and if our usual winter temps the bottom would still get too cold it would just take a lot longer. One could also add a riser to the diffuser base if not concerned about water level and keep diffusers at the 3 ft below the surface, Three ft seems to be the magic number to me as anything less does not have enough lift to create much water movement.My best approach on DW seems to be with Sonar AS and then maintain 10-15 ppb with the PR formulation all winter.This usually keeps us from doing a second AS spring application.Seems different types of DW germinate by long days/ short days warm water,cold water etc etc which has made DW very adaptable and a real survivor.If my main goal was DW control I would keep the water moving at the surface and monitor water temps in the bottom 4-5 ft and not allow the bottom to get less that 40-42F. I am not sure what seed longevity from a germination standpoint is with DW,especially since there are several types I would suspect many years. I know many small seeded broadleaf weeds seeds can lay dormant 10-15 yeras before the right conditions exist for germination. This would be a great topic for SePro to weigh in on, Ted
