Pond Boss Forums GENERAL QUESTIONS Property Projects & Construction Worrying about winter fish kill

Hi gang! I have been concerned about my ice and snow covered one acre pond and it being newly stocked as of last Spring. Will a covered pond kill the fish? I assume it would eventually, but at what point do things take a turn for the worse. It has been competely covered for approximately ten days and there looks to be no relief in sight as the temps the next 10 days are going to be below freezing. Currently it is 5 degrees here in Cenral Iowa! I wonder if Siberia is colder �..

Thanks!

Can you get onto the ice and clear the snow off with a shovel?

If your ice is clear, at least the sun will then be able to penetrate it.

Better information and advice will be coming along soon.

Do you have a diffuser system in the pond that has been shut down? I've actually broken some ice and pulled one of the lines and diffusers in close to shore and cranked that one up. In fact just did it in my trout pond several days ago. Opens the ice right up above the diffuser.

BTW it takes time before oxygen is used up in the pond unless your pond is extremely weedy.

New ponds (1-5 yrs) rarely have winterkills because not very much dead weeds, leaves, and thick organic muck have accumulated to cause a large loss of oxygen due to slow gradual decomposition during the winter. Also if the pond gets wind exposure the wind eventually blows some of the snow off the ice and polishes the ice smooth so snow doesn't stick very well to the ice thus is stays fairly snow free. Light penetrating into the water through the ice will allow phytoplankton and attached algae growth on the bottom to make oxygen thus newish ponds very rarely have winterkill unless the thick snow lies on the ice for 5-7wks (for new ponds) keeping the underwater world completely dark.

I am glad that we still have mostly ice without snow on it. I am not sure if it was wind or temps that kept the 4" that fell from building up on the ice. I am considering a bubbler/aerator after all these years (had one fish kill a couple years back under prolonged snow over ice). Not sure what the cheapest system might be if I only used it to open ice when snow stayed on ice for an extended time? I would prefer to run large diameter pipe (maybe 1.25" diameter poly pipe) for the hundred or so yards from the barn to the pond, and then traditional air line from there. Would that work? How deep does it need to be buried? I want to keep the compressor in the barn.

A point about the use of aeration in winter.
If the pond has had a chance to stratify placing an aerator in the pond can have the opposite effect of what is known as reverse aeration.
This likely will not affect those in states where there is little ice.
But with a pond with heavy weed growth or a significant algae bloom snow on the ice will stop light penetration causing plants to die.
As the plants die there is a buildup of gases carbon dioxide, hydrogen sulfide, sulfur dioxide, and methane. All of which are will settle to the bottom of the pond slowly building up from the deepest areas until eventually it reaches the entire pond. Winter kill or winter anoxia.
Placing a diffuser in the deep area of a pond after this has begun can circulate these gases throughout the pond and accelerate the anoxic conditions.
If you plan to use aeration start it early or in shallower water to reduce this risk. You can alway move the diffuser deeper after the pond has opened up if you feel it is necessary.
http://files.dnr.state.mn.us/publications/fisheries/investigational_reports/547.pdf
While this was not a particularly successful experiment it will kill many game fish.

Thanks Barry. Something we've been preaching here for years.

RAH:

That would work. How deep to put the line? If you put it in above the frost line, it is important to make sure the airline has a drop all the way to the pond, with no dips where moisture can accumulate and freeze. Running 1.25" poly will minimize the possibility of it freezing solid, but to be safe, treat it like a drain. 1/8" slope in 10' of run. If the ground slopes from the barn to the pond, just check the drop. You might have enough natural drop already.

To keep ice off of the pond, larger bubbles to create surface wave action is better.

Put the diffuser 1/4 to 1/3 the max depth of the pond. Place it close enough to shore so that if anything went into open water or broke through the ice near the diffuser that it could get out easily without having to climb up onto the ice. Been there, done that and almost lost my two dogs because of it.

Just remember that the "cheapest" system might not be the most cost effective system for the long run. With that said, look into the system that RC51 built. That might be the most cost effective system for you. Splurge and get the self-sink hose for the pond. You can thank me later....

Thanks for the tips! The barn is actually substantially lower than the pond, so I will need the condensate to drain back toward the barn. I will need to figure out how to do this - maybe a pit? I have several compressors for operating air tools. I wonder if they might work for occasional use? Thank you for the warning concerning placement near shore. I would not have thought of that. I was also considering using bricks to sink the hose, but will now will invest in sinking hose for the short section that will be submerged. I greatly value experience! BTW - I should have said "most economical system long-term".

The compressors that are used in aeration systems for ponds are oilless...... I won't recommend using an oiled compressor.

Check into the diffuser CFM operating range if you are doing a DIY system. Also, don't run a lot of air pressure to the diffuser. Typcially all that is required is 3/4 psi or slightly less per foot of water depth at the diffuser location.

Another great tip! I will invest in a fit-for-purpose compressor. The pond may have one hole 12-feet deep, so I could put the deffuser in 3 to 4 ft of water based on your suggestion above. I would have thought it should be deeper and would probably have put it in 6' of water without knowing any better. I got a PM suggesting that I contact a member of the PondBoss forum that could help me out when I get ready to spend some money. He has been a great source of information for me on this site, as have you.

One source of tubing that is reasonable priced is the black water pipe that comes in 100' or 500' rolls and in various sizes. There is a better grade that works for higher well pump pressures and a cheaper low pressure grade. Either one should work well for aeration as you would normally be working well under 10 psi. The cheaper version is often not available from plumbing houses but sometimes they have both. This vinal water pipe is available from most large plumbing wholesale suppliers and is also available from Lowe's and Home Depot in the section where they sell the supplies for home well systems. It usually is not in the regular plumbing section but where the well plumbing is.

The places that sell aeration also have the non-sinking pipe which I'm sure is fine. The reason I mention this water pipe is in our case the other requires ordering it and waiting a week for it to arrive. I can go to the local plumbing place and get what I need when I need it. It is also cheaper than what the aeration places sell and may even be heavier stuff.

Just another possibility if you find you come up short on pipe length.

I actually already have the low-pressure poly hose already from a previous project. I just am figuring out how to dig the trench, especially across the gravel driveway. I will likely only go 12" deep to avoid a main electric line (600 volts) that is buried deeper (I will have it marked before crossing it. I am in no real rush, since its too late this winter.

I have used an aeration system about three weeks and currently waiting for spring to do the final installation (stuff back in boxes right now). So I am not an expert by any means.

One solution to the barn being lower would be to run your compressor into a small tank. Like say a tire "air bomb" type tank or an old small air compressor tank that the compressor had went kaput would be even better (has multiple inlets and often a drain). Anything safe holding 10 psi would be safe. On the bottom of this tank have a drain where you could manually drain off condensation a couple times a winter. Run the air from the compressor in the top and the air out to the diffuser from another port. This would allow the water to condense and settle in the tank before the air reaches the line going to the diffuser.

You could also make something out of PVC pipe (unsafe for higher pressures but 10 psi not much danger). You could also buy a commercial air line drier like used for paint guns and plasma cutters. Lots of possibilities. Just get the air dry. The aeration people might even make something specific for the purpose I am not aware of.

Then make sure the line drains back to this tank with no dips to the point where the line goes down hill to the pond. Let the condensation from the lines come back to the tank instead of the pond.

If the drive is higher than the surrounding ground, and it's not rocky where you want to run it, take a 1 1/2" PVC pipe, start digging a hole beneath the driveway and use a hose to wash out the dirt in front of the pipe. Stop every once in a while to pound the pipe further under the drive, and wash out more dirt. The dirt usually comes back out of the pipe with the water. Keep doing that until the pipe comes out the other side. The same process can be done with a trench/pit on one side and a pit on the other. If your aim is good, the pipe will end up in the pit on the opposite side of the driveway.

For the remainder of the trench, I've rented walk-behind trenchers - much easier and quicker than hand diging a trench.

Thanks for the idea on the tank. I am considering a backhoe attachment for the tractor. This would be one more project to justify it.

Just thinking you should have a back flow valve just in case you manage a siphon while rearranging the aerator. I dont think you want to drain the pond into the barn.

Good catch! I forgot about that. If the upper part of the rafters in the pole barn/garage are above the pond level, I'd also run the air line up over the level of the pond, then back down and out to the pond. (before going into the drain tank). Extra insurance if the check valve were to leak a little.

Might not even be bad to put the pump up in the rafters if a person had good stairs or ladder so it was easily accessible to service it and make changes if needed.

Why not just use a check valve?

Thanks again! I will put the compressor on the second floor of the barn above pond level and include a check valve near the pond too. No harm in using a settling bowl for moisture on the compressor side either. Great advice!

Because mechanical devices will fail at some point. Maybe not this year or the next, but they will fail at some point. I sure wouldn't want to risk flooding my building!

I like double safeties, but placing the compressor on the second floor should be pretty safe unless gravity fails. I will probably use a flapper type back-flow preventer also, since they are pretty robust. I am hopeful this will help with condensation build-up also.

Disc type diffusers exhibit a back flow prevention characteristic as part of their design. Non-mechanical, and only one moving part...the membrane itself.

What type of aerator is best for opening up ice?