Insulating Koi Carp Pools – Considering Options

Koi Carp Insulated with Euro-matic Balls

Our pond is heated, with the thermostat set at 15 degrees C (59 degrees F). Whilst I worked from home, I could see steam rising from the pond each morning, basically watching my money evaporate. Urgently, I needed to consider options for insulating koi carp. Covering the pool was required, but I needed to work out what properties must it have.

  • Our rear garden windy so it must not blow away
  • Cannot cause any damage if it does blow away
  • Cannot look too ugly
  • Able to pack it away for the summer without needing a second garden to store it
  • Still be able to feed the fish easily
  • Fish must not be able to strand themselves by jumping on top of the cover

What we considered:

  • A cover like David and Audreys
    • Unfortunately, a pergola will shade our and our neighbours’ gardens
  • Temporary frame to attach the cover
    • Frame needs to be strong to cover a pond 6 metres x 4 metres, irregular in shape on one side and built upon another. Secondly, it needs to be securely anchored to the floor
  • Floating swimming pool covers constructed from polystyrene slabs covered on PVC
    • However, fish can jump on top. Even more, when I enquired, I was informed PVC leaches chemicals.
  • Plastic balls –
    • Also covers drinking water reservoirs near airports to discourage waterfowl
    • Various sizes are available to suit your specific size pond, the distributors helped us choose 50mm ones
    • Automatically spread themselves out on the surface and move into all the nooks and crannies of an irregular-shaped pond, including the skimmers if you’re not careful
    • Rarely get blown out, but when the fish bred, they threw out about one thousand balls in one day! However, they cannot do any damage if they are blown away
    • Available in various colours but we went for clear, to allow light into the pond
    • For extra insulation, they can be stacked into multiple layers

Manufacturers of pool insulating balls claim:

  • Heating costs reduced by 75%
  • Evaporation reduced by 90%
  • Reduces penetration of Ultra Violet rays, precluding growth of algae and clogging weeds
  • Ice formation rate is reduced in freezing conditions, lowering the ice formation point by up to 10°C (50°F)

Anything else?

Geometric shapes are formed on the surface of the pond after the wind has blown them about a bit which does look nice. Feeding the fish is still easy and they appear to enjoy pushing the balls around. I used pieces of waste pipe to form a 1m x 1m area, without balls, for feeding.

Storing the balls is simple, just place them back into the plastic bag and cardboard box they came in and store them in the loft. Though the only downside is that they can get covered in algae on the bottom. So, we are going to add salt to the pond this winter and hopefully, that will solve the problem.

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