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avepico

Above Groud pond in greenhouse

avepico
11 years ago

I am planning on building a above ground pond in my greenhouse; 4 feet wide, 2 feet deep, 3 1/2 feet tall. In zone 5, does anyone have an educated guess on what it would take to keep it warm enough to keep fish thru the winter. I am going to build it either way, just want to plan on fishes.

I am planning a solar power set up for minimal needs at the greenhouse, could add enough for a small air pump and small heater.

Comments (12)

  • kudzu9
    11 years ago

    avepico-
    That can be estimated. However you need to say what average temperature you have during the winter and what temperature you want to keep the tank at. In addition, it will make a big difference if the bottom and sides of the tank are insulated. If you can provide this info, I'll take a stab at calculating it.

    However, I suspect that the size heater you would need to keep the tank at the temperature you want will require a large investment in solar to power it.

  • avepico
    Original Author
    11 years ago

    Simply put, I can insulate it easily if needed. My target temp would be between 30 and 40 degrees with an average around outside temp of 10 degrees.

    I am looking at a solar system with a 150-200 watt panel and battery/batteries.

    This is my model or experimental design that I will try, tweak, and then take my learnings into a larger setting. I have hopes and dreams that I will never be able to pull off if I don't start small.

  • kudzu9
    11 years ago

    Give me a day or two and I'll get back to you with an estimate.

  • Fori
    11 years ago

    What species fish?

  • avepico
    Original Author
    11 years ago

    Just some white mountain cloud minnows ATM, won't go more extravagant until I work out any wrinkles this year.

  • kudzu9
    11 years ago

    avepico-
    I have had to be gone but I am back this weekend and will try to do an estimate for you as I promised shortly.

  • kudzu9
    11 years ago

    avepico-
    Sorry it took so long to get you some numbers. Here is my rough estimate for you based on the dimensions you gave me and these assumptions:

    Temperature in pond: 40F
    Average surrounding temperature: 10F

    1" styrofoam insulation on all sides, and on the bottom

    Top has a layer of visqueen or glass over it.

    Based on this I got an average heat loss of about 150 watts, with about half of it going through the sides and bottom, and the other half through the less well insulated top. If you used a double layer on top (like a thermopane window or bubble wrap plastic), you might be able to reduce the power need to about 120 watts.

    These are just rough calculations, and based on averages, but at least it gives you a ball park number. If you have an extended cold spell (below the 10F temperature) you would need more energy to maintain the pond at the desired temperature.

    Hope that helps.

  • avepico
    Original Author
    11 years ago

    Thank You very much Kudzu. This certainly puts it beyond the realm I am going to be able to do for at least a couple years in an alternative energy setup.

    Just have to dust off the old 90 gallon tank in the basement and overwinter in that. Plenty of time to plan ahead for it.

    Again, thank you for the numbers.

  • cole_robbie
    11 years ago

    It's easier to keep fish alive in winter than it is to keep them through the hot summer. I had a tank of bluegill that did great...until the outside temp got into the mid-90's. When the water heats up, it can't hold enough dissolved oxygen, and the fish die quickly.

  • kudzu9
    11 years ago

    avepico-
    You're welcome. It's just an engineering estimate...but I'm sure it's in the right ballpark. I was actually surprised that the amount of energy required was that low, given that you were talking about a container with about 200 gallons in it, and a pretty cold environment.

    In any case, good luck. I'd be interested to hear what you end up doing and how the setup performs.

  • avepico
    Original Author
    11 years ago

    It's actually amazing how well it has been going. Daytime highs have been mid 90's to low 100's and the fish are loving it.

    I have water lettuce and anacharis for cleansing and aerating the water, supplemented by a very small fountain for movement. I have a slight issue with algae on the sides and bottom since I am still dialing in the proper amount of food.

    However the water is almost perfectly clear. Did a water change today and the water I remove had just the slightest green tint. My plants should love that for watering.

    I had started with some feeder goldfish to test the waters, as it were, and they couldn't take it. After the initial dieoff when I found out we have chlorine in our tap water,the survivors were at the surface every morning gasping for air. The minnows don't have any problem and I believe I saw them spawning yesterday morning.

    It's not a completely finished product yet, probably never will be, but it is going great so far.

  • cole_robbie
    11 years ago

    That is great. Good for you. Are you shading the tank itself from the sun? I would guess that the water plants provide some shade.

    Have you taken the temperature of the water on a hot afternoon? I would be curious how it relates to the hot outside air temps.

    I was trying to keep some big bluegill. I'm now reading that larger fish require more dissolved oxygen. So maybe smaller fish are easier to keep, or at least less sensitive to the water getting too warm.

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