Maximum - There is a lot of previous discussion here regarding winter aeration. Here is just one link that discusses it. However keep in mind the climate where you live compared to comments from others who live in areas with milder winters.
http://www.pondboss.com/ubb/ultimatebb.php?ubb=get_topic;f=20;t=001274 Please come back here and let us hear about your efforts with winter aeration so your experiences can provide more information to those with ponds during harsh winters. Thanks for using Pond Boss.
A forum member - Wood - also lives in an area with similar winter conditions to yours. Here is a copy of his testimonies regarding his experiences with trout in a small Canadian pond.
CODY SAYS - Aeration can increase the chance of open water during ice cover that allows sunlight penetration and microscopic and or benthic plant activity. Snow removal from the pond produces the same benefit. A PB forum member WOOD proved that snow removal was adequate for a northern Canada trout pond with 3 ft of ice cover during winter of 2004-05. See his testimonies below.
WOOD SAYS - I can share what has been working for me, I won't call it advice, as I am still learning also. Air pumped into your pond contains about 20% oxygen. Air produced by plants and planktons is near 100% oxygen I believe. My trout have successfully wintered two years now with 200 days of ice cover, max ice thickness 37" with seven feet of water below. No aeration, but I removed snow cover within a few days of new snowfall on about 3/4 of the pond. I tried to aerate two winters ago and had problems with airlines freezing (see items below for his problems) . Lower fish densities probably helped with keeping DO levels up also. Most ponds around me do not use diffusers in winter, either nothing or top water splashers.
I just managed to remove snow yesterday, took three hours of plowing just to get the truck to the pond. I plowed most of it to one end, then drilled a number of holes close to the piles. The weight of the snow forced water out the holes for most of the day. Instant skating rink. I also dropped the camera down and found the fish alive and well. I will not start up aeration until around May.
Bill, as proof to your comments on light penetration, I have seen a significant increase in the trout's activity level since removing snow. I watched their movements before and was shocked at how lethargic they were and also how the fishing has improved since plowing. I fish many more days on ice than open water and we do become very familiar with ice conditions and types. I currently have 37" of ice and considering the water level was down to about 10 feet before freeze-up, only leaves 7 feet of water. Trout are pretty resilient I'd say.
Wood goes on to comment after his first winter experiences, that after trying to maintain aeration through last winter and dealing with frozen airlines, I have decided not to aerate at all this winter. We also skate, ice fish and DRIVE vehicles on the pond and would not risk an accident with thin ice. I will shut down the compressor at first ice, early October and will re-start when ice is completely off, April or May usually. I plan to remove snow from two-thirds of surface once it is safe to walk on and keep it free of snow. I had no fish kill doing this last winter with ice thickness of 36". I did not change my compressor run times at spring startup, 6pm to 8am and my pond did not stratify this year.
For me at least, snow removal is more important than winter aeration. You make a valid point regarding the impact of BOD on whether winter aeration is necessary, and I do not know the answer in your specific instance.
I did over-winter trout for two years successfully with only snow removal (and lots of it). My pond is less than a quarter acre with around a 100 trout from 12" to 16" at that time. My pond is also only about three years old which I believe helped. I did get around 200 days of ice cover and no fish kill.
I have since moved my family north and have rented my property (and pond) to a young couple. The husband seemed quite enthusiastic about fishing and pond maintenance. Last winter he was instructed to remove snow as part of the "deal" if he wanted to have fish to catch. I realize you do not want to experiment and risk loosing your fish, but it did work for me.
Trout Status - I measure water temps and have noted that this year with my aerator setup (open water operation), my pond remained de-stratified all summer vs last year without aeration. I raise trout and find them at all depths including bottom. So I can tell you I have both adequate DO and turnover, but I don't measure how much.
PUMPS -The 1532 would easily mix your pond. I have a Gast diaphragm compressor, .9 cfm at 10 psi. I run 300 feet of 1/2" poly connected to a weighted garden soaker hose. My pond is a little larger than yours and my Rainbows did well through a hot dry summer. I ran it 24/7 until the heat of summer and then only when air temps were cooler than the water temp, usually at night or cool cloudy days. Since I have trout, I have to be careful with warming the water and my system easily de-stratified my small pond. The $40 price tag is too good to pass up. 3/4" black poly water line is cheap as is the soaker hose. Should work excellent for you. Btw, the soaker hose idea was from Bob Koerber, some time ago. This may not apply to you, but it didn't create enough surface boil to keep an area ice free this winter. No suprise for me.
I use a Gast diaphragm compressor, .9cfm, 1/8 hp. 300 feet of 1/2" poly run to the pond. Diffusor at 13 feet deep. My pond is small also, 180ft x 50ft. I run for 12 hours nightly till freeze up. It's been two years, trouble free, except for frozen airlines when I tried to run through last winter. This unit will handle higher psi than vane style.
WINTER AIRLINE TROUBLES �
I have 300 feet of 1/2" poly airline running to my pond. It froze up once in December after a warm spell, temps went from -30c to +5c then back down again. I imagine there was condensation from the swing in temperature. I dragged it out of the snow and cut off about 250 feet and brought it in the house to thaw. I then blew it out with the shop compressor, put in a little methyl hydrate, re-connected and everything was fine.
About two weeks ago it froze again. Temps have been reaching -40 here for awhile now, so I have not bothered with it. It's enough trouble keeping vehicles running and commuting to work every day. We also just got a huge dump of snow and now there is over two feet on the pond, which I'll plow off with the 4x4 this weekend to let some light through.
I did not bury the airline originally as the frost line is more than four feet down. Water lines here are at eight feet otherwise they will freeze.
The compressor is unheated under my home. Airline is downhill to pond. I think any moisture freezes before it has a chance to drain down and the i.d. gets smaller until blocked totally.I think rather than trenching airline, I will trench power instead, as it would be handy at the pond anyway. Next summer's project I guess. Dave, +5c in December is highly unusual here and felt quite warm indeed. Cecil, ice came off lakes last year on May 24th. Ice on my pond is well over 30" currently. Almost half way to spring now.
The airline was frozen in two places, one about 75 feet from the compressor and also about 50 feet ahead of where it enters the pond. Robert B's comment regarding splices makes sense and I think a larger i.d airline may also help my situation. Norm's 4" pvc pipe idea is also good, I will use this next winter. I think I will end up putting power at the pond next summer to eliminate this whole problem. I would like it simple and hassle free, at 40 below, you just can't be messing with stuff, skin freezes quickly.
Aerator has been shut down for a month now and temps are up again to just below freezing. We got dumped on again, snow is almost three feet deep.
