The fish have left the pool!
We have a children’s 12′ diameter swimming pool in the atrium garden off of the kitchen. We run it without any filter or chlorine – just all natural spring water, children and fish. It has been the home to our comets for seven years now. On a per gallon basis it must be one of the cheapest aquariums around – $30 for 1,800 gallons. Quite the deal and a great place to cool off after morning chores and construction projects.
This year we added a solar hot water heater to it by running the pump output through 82′ of 1″ black plastic water pipe which sits in the sun on the stone wall beside the pool. This was another one of our science projects with the side benefit that my wife Holly pronounced the pool swimmable while it was still only May – quite an accomplishment in our climate. She won’t go in until the water gets over 75째F and doesn’t like it until it gets over 80째F. The water coming out of the spring that I use to fill the pool is 45째F, cold enough for refrigeration. The 82′ of solar heater raise the water coming out the far end by 2째F above the input temperature. I was quite pleased with the results and it made a great project for our homeschooling to boot.
To keep our super simple solar hot water heater from acting as a lunar chiller at night the pump is on a timer so it doesn’t come on until the pipes are already being heated and shuts off when the sun goes off the pipes in the afternoon. This also saves electricity by only running the pump about six hours a day.
From the plastic pipes on the wall the water splashes down into the pool which is pleasing to the ear and serves to aerate the water for the fish, although I think we probably do a good job of that when we go swimming too!
The fish are fun to swim with but they also serve a function. They eat any insects that think to use the pool for a breeding ground. (Yes, I’m talking to you mosquitoes out there! Fortunately the fish love your wiggly little babies for snacks!) Sadly the fish treat mayfly and dragonfly larva the same way so although we often see these winged crusaders dipping their tails we’ve not yet seen any dragonfly larva in the pool. They do live in the animal watering troughs and various ponds though so we get to see them there.
In August the challenge becomes one of keeping the pool from overheating but by then the sunflowers around it have grown up tall enough to shade both the solar hot water pipes and the pool. A simple an elegant solution that uses one of my favorite flowers.
We had intended to run the pool later this year but the liner developed a leak which we haven’t found yet so we transfered the fish into a 50 gallon planted fish tank in the kitchen. Now they can look out at their old more spacious home and long for it come next spring. In the past we’ve tended to leave the fish out under the ice in the pool which works very well. So much so that in the spring it is not uncommon to find more fish in the pool than there were in the fall…