i made one several years ago that worked good. was a combination solar and geothermal. my water tank was not that big, about 10 foot round and 3 feet deep or so. i had a small solar panel that i made, 3 foot by 3 foot with two tubes that basically just stuck in the water. then under the tank i dug 5 8 inch holes 4 feet deep and put 8 inch sewer pipe in it and set the tank on top. then i put styrofoam insulation all around the sides of the tank. when it was really cold and windy, it would get slush on it but if the wind was not blowing it stayed open. most time the cattle would crowd around it and that would help keep it open as well. other option, but wastes water, was to let it overflow and keep filling it with fresh.

I really appreciate all the comments. Camperman, I believe my pond is currently only about 150 gallons, though at first I really overestimated it to be about 600, lol. There are so many rocks inside it that it might be less than that. The first year I had a rather powerful pump and extremely good waterflow down the falls. Everything I had read led me to believe the water lilies would not bloom, but they did. The next year, I had to replace the pump and got one that had a fountain. That decreased the flow down the water falls so as not to disturb the lilies, but a combination of too much shade and probably not enough fertilizer led to less blooms. Then about the time they were looking good, a raccoon tore the whole pond apart. It has never really looked good since. I think I am going to go with the Savio compact skimmerfilter that will go on the outside and buy a pump that will fit inside it. I doubt if the one I am currently using will fit. The $ are adding up, but I don't have a lot of time to constantly be cleaning the pump which now lies on the bottom of the pond. I took a look at a 100 gallon stock tank today to make sure there was enough flat vertical surface area in the top tier to cut through for this skimmer and there is. Thanks again for the suggestions and advice everyone. Sherry

Uhhh..., I think you would need to have some sort of "off" anywhere there is an inlet or outlet for the water or anywhere a vacuum is formed since that would cause a backwash. I am assuming she means the bio-falls has a gravity based outlet and a submerged or gravity based inlet Ann, we need a bit more info...and you need to know more about the system or you will be attached to the landscaper for the life of the pond. If he is a good landscaper he should have given you the info in the first place. Please don't be alarmed about the number of questions. No two ponds are alike and no two ponders are alike either. How much water is in the pond system? How big is the pump? Where is it located? (in or out of the water?) How big is the filtration/bio tank? What material is the liner? Do you have fish? What kind, what size and how many? How deep is the pond? How and where does the water enter the upper bio-falls? Why do you turn off the water? Do you have rocks on the bottom of the pond? What zone are you in? We (all of the ponders who will come in to talk about the system) may give you advice that seems to conflict. Say so and we will try to reconcile the answers. If you have no idea in the world what we are talking about, say so. Some of us can get wordy at times. This is a bit off season for many of us so the process may be slow but you can be sure to get responses. Sandy

Sheepco, thanks for the picture and explaining your set-up. That really helps. So pretty, too. I think I'm going to try this "diverter" valve. It's cheap enough to find out I don't like it and get one or 2 gate valves instead (2 would be ideal). I'll post my "review" when I get it going. Now I'm just deciding whether I can work in a pretty stream in the next year. If I think I can - bigger pump! If not, might as well spend the extra $40 on plants. Mamasue, I'm not sure what a TT is either but it sounds like your tank is the same size as mine but your skippy is bigger. I'm not TOO worried about green water. That is to say, I'm willing to let it cycle and be green when it needs to but I was thinking a 20 gal skippy with a 100 gal veggie would be enough. Can I ask you for more info on your bigger pond? What your filters are, how big the 2 pumps are, how long you've had it running? Gee are those enough questions? I'm sure I can come up with more for all of you!:)