If I ever have a pond with fish again I want to try it. It would probably drive my cats crazy though LOL (Use a heavy glass vase and invert it on some concrete blocks so they can swim in from the bottom. Submerge the vase and turn it up under water so the vacuum created keeps the water inside. Make sure you have a heavy glass container or the weight of the water will shatter it.)
During the summer, algae growth can be a huge problem in garden ponds. The great news is that there is an easy way to keep pond water clear without using expensive chemicals. Here's how. | GetBusyGardening.com
This advice is intended for anyone installing a small (under 1000 gallons - about the size of 10-person hot tub or less) prefab garden pond or other little container pond on a patio or balcony. I've had several different types of ponds over the years, and, after a few learning curves, I've got a system I really like—easy to care for with healthy water, plants, and fish.