Should I cover my Koi winter storage tank?

[JimLauraEyez]

My wife & I live in central Wisconsin. When we had our house built we put a pond in the front and put Koi in it. Then we had the delmina of winterizing the fish. Last winter we bought a 144 gallon horse trough which we put into the garage. I also put two heaters, two aerators, and two water filters..We had a lot of evaporation, so much so that we got mold throughout the garage. So I bought some Plexiglas to cover the tank.
This year I decided not to heat the water thinking this was the cause of the evaporation.

My question is weather I should cover the tank or not with the Plexiglas. I want to stop the evaporation and therefore prevent the mold from starting again. My wife says to leave the tank uncovered.

Thoughts/suggestions? Will covering the tank harm the Koi?

 

[Tula]

I think you should keep the tank covered. I know someone who kept their koi in the garage for three years, and covering the tank is what stopped her garage from being a rain forest.

 

[MitchM]

Yes to cover.
No to heating.
Keep water circulating and filtered, leave a gap in the plexiglass cover so you can have good gas exchange.

What size are your koi and how many do you have?

 

[JimLauraEyez]

Tula and Mitch. Thank you for your advice. We have 5 Koi sizing from 6 to 10 inches. We had five 10 inch Koi last spring but we lost 4 of them due to my inexperience. We do have about 50 fry which we'd like to get rid of some how.

 

[MitchM]

You're welcome, JimLauraEyez, and welcome to GPF btw.

I'm concerned that your setup may not be sufficient to maintain your fish over the winter.
That's a lot of fish for a small container.
What are you using for filtration equipment?
Do you have a water quality test kit?

 

[bettasngoldfish]

It's also a good idea to have a cover so you make sure the fish stay in the tank.

Sometimes you get a jumper and they end up outside of the tank. Doesn't usually end up well for the fish.

 

[sissy]

Do you test your water and you should also have a dehumidifier .I over winter my plants in my basement and have one going .You don't need an expensive one .But if you have 2 heaters you should be able to keep them out side .The stress of moving them as they get bigger is not good .If colleen can keep hers outside in Canada you should be able too .How big is the pond and how deep is it .She now made a cattle panel cover for her ponds and it works great at keeping the water warmer .