It’s 18 degrees fahrenheit (-8 degrees celcius) outside. I’m looking at my small peanut-shaped fish pond. On one side I have a 100-watt pond heater. On the other side I threw a bubbler stone for a standard aquarium. The air pump I use says it takes 8 watts.
From the surface, it seems that the bubbler is doing a better job in keeping the ice away than the heater. Why is that?
I can understand that ice has difficulty forming when the water is moving… but doesn’t the pond still lose heat faster trough the water surface than through the air? So is the pond becoming super-cooled because of the bubbler?
A bubbler works by stirring the water and bringing warmer water from the lower levels to the surface, right?
It would seem that in a small body of water, eventually all the water would be lowered in temperature and it would freeze. perhaps all the way to the botttom!
I have friends with bubblers keeping ice away from their boats, but this is in large lakes covering many hundeds of acres. There’s just too much volume there for a significant temperature drop to occur before Spring.
With the heater you’re actually adding energy to the water, so I’d guess that in a small body it would work better.
How big is your pond? 200 gallons, 500?
If I’m incorrect in my guess, I’m awaiting enlightenment.
I have a 2000 gallon pond that’s gone through 6 Wisconsin winters. I started with just a heater and the first two winters I lost all my Koi (the Shubunkin and Sarasas survived).
I then added a bubbler and a small fountain pump. This did the trick. It kept a large 5 foot diameter hole in the ice. The only problem was that the pump tended to form a ice dome over it when it got really cold.
So I switched the pump to only roil the water surface rather than create a small water column. This works a lot better.
This past winter I got everything all set up, but forgot to plug in the heater. Everything still worked well until we had a week-long cold spell. Then, in spite of the bubbler and the pump, a layer of ice formed anyway (except for about a couple inch diameter hole). I plugged in the heater and I got my bigger hole that I need to keep the Koi alive.
The conclusion I draw is that neither the heater nor the bubbler is sufficient by itself.
Clearly though, a lot depends on the size of your pond. A smaller pond will probably work with either method.
One more thing, it’s important to make sure that with any of these methods that the warmer water at the bottom of the pond is not brought up to the surface to cool. In other words, the bubbler should only be a few inches below the surface. If it is at the bottom then it sets up a convection current and the water at the bottom becomes too cold.
[edited to add…] To address the question of how the bubbler works. It’s intended to simply keep the surface moving so it doesn’t freeze. If one puts it too deep though, then it will bring warm water to the surface which will of course keep the surface from freezing… but the fish may die due to the water being too cold.
I used to work at a plant that had its own millpond with a large dam. They used a bubbler rather than a heater to keep ice away from the dam. It worked amazingly well, only failing to keep ice away from the dam when the temperature dipped appallingly low. I don’t think it worked by bringing up warmer water – I’m sure it works by keeping the water in the vicinty agitated, and preventing formation of a stable ive layer near the bubbler – ice simply can’t get a “foothold” if the thin layer that forms is broken up and churned by the roiling surface (when the pond got really cold, the ice seemed to get around this by letting chunks of already-formed , thick ice layers down to the dam, where they got stuck. Being already formed, they didn’t have a problem with the bubbling water under them. If you have bo current in your water tank, this shouldn’t ba a problem for you,)
Thanks for the tip. This is the first winter that I’ve owned the fish pond, so I didn’t know that. The bubbler is now resting on the bottom - I’ll be sure to move it when the ice clears. But it does make sense that this would be chilling the whole pond more than I’d like.