My pond is small: 5X8, 2 1/2' deep = 160 gals.

In the fall I cover my pond with screen to keep the leaves out. I put boards across the pond and then the screen on the boards and over the stream. This year I may build a framework if I have the time.

When cold weather hits, I put clear plastic over the screen. I keep a small part on the south side open for escape of gases. So far, in 3 years, the pond hasn't completely frozen, even in below zero weather. I have a de-icer if I need it, but haven't needed it so far.

I keep the pump running all winter too. I disconnect the hose from the stream and drop it down into the water and that keeps the water circulating all winter. Haven't lost any fish this way.
Anne

Hey, Cindy. The subject of pond coverings for winter protection is covered infinitum every fall and sometimes begins in early summer. Major discussions have been slight this year. I must admit the concept of a yert has not come up, to my knowledge. I may be totally out of the loop on that one but many posters have built greenhouses over or in their ponds. In your zone you shouldn't have too much ice to begin with but to give you a good answer we need to know a few things. How big and deep is your pond, in ground or above ground, do you keep fish, what kind of construction surrounds the pond, waterfalls? Are you in the city or country (aesthetics, building permits, neighborhood associations), why are you thinking of a cover? How labor intensive a project are you willing to deal with and how pricy are you thinking to allow?
For myself, I've always been happy to tinker and try new stuff so each winter it has been different and has ranged from a full greenhouse covering to just a deicer. The pond has grown from a 100 gallon preform to a 1000 gallon EPDM lined, far too small(as soon as possible to be enlarged) pond.
I am bemused by the yert( a semi-permanant fibrous construct for semi-arid climates). Do you have any information to share? Sandy

If your pond is deep enough and you keep a bubbler running (and deicer when needed) all winter your fish will be just fine. I know people who don't even bother with a bubbler and let the pond freeze totally over and their fish survive. Not sure I'd want to risk that, but as long as the pond doesn't freeze solid you'll be OK. In my area I wouldn't bother with a cover because it would be a constant battle against winter winds continually blowing it over or snow weighing it down into the pond. It would have to be anchored very securely into the ground or on top. To me that would be more trouble than it's worth and not really needed.

Sandy,
I don't have too much info on the yurt dome but here is a website that might interest you. http://www.shelter-systems.com/large.html
As for my pond it is 25x30 and 3 1/2 feet in the deepest part. The pond is an aquascape one but in addition to the biofilter we have a bead filter and uv sterilizer which has greatly improved our water quality and made this years ponding a pleasure. my fish seem to be thriving and I would love to actually see all of them during the winter...hence the dome...I have 5 20 inch koi which I have raised for a few years since they were about 6 inches long and numerous offspring. We are in the country but have neighbors surrounding us. We do have significant ice covering the pond during the coldest part of the winter... although with a solids handling pump manage to keep a nice hole in the ice for gas escape. We pretty much hold our breath until spring hoping that the fish survive. I've grown rather attached to them. (my largest koi swims right through my hands and I can just about lift him out of the water with no sign of fear on his part and he does this over and over again as though he enjoys it as much as I do...it's so cool

Do you have significant snow with that ice in your area? Snow on a yurt type structure sounds like a collapse diaster waiting to happen in the dead of winter.

I've not built a cover personally but look to the roof lines of homes in Vermont and New Hampshire - the salt box - so snow can slide off.

Just how much sitting outside do you plan to watch your fish. I also like to see my fish in winter and I often can because ice is hit or miss here in my Zone 7b, but it is for but a passing moment or two while filling the bird feeders because it is cold. I enjoy the winter because I don't have to fool with the outside for a few months. Instead sit by the fire with a drink and a good book!

Sounds like you might do better with a winter enclosure you can enjoy and keep semi-heated like a full-blown green house. Grow some tomatoes on the side!

I found a link for something that might interest you (if you haven't already seen it). Maybe you could build something yourself if you didn't want to buy one.

Also - more permanent and costly, but can be lived in:

http://www.pacificdomes.com/faq.html

Here is a link that might be useful: Shelter Systems

commetose,
I looked at the pacific dome website. They are great!!! I would imagine the expense far out weighs the greatness though. I just wondered what other people did and if they miss their fish as much as I do in the winter.