We had a pond /waterfall that was enough trouble with leaks that we are going to turn it into a rock garden with a self contained fountain. My problem is what to fill the pool with. We cut the liner out (it's about 6ft x 6ft and 4.5 ft deep). It's pretty much non-absorbing clay beneath. Our sprinkler system will hit the pool and between the rain and the sprinkler it (the pool) being empty has about filled up in a couple of weeks. I'm afraid that if i fill it with dirt with a layer of rocks on top to set a fountain that it will turn into a mudhole shortly. If i fill it with gravel/rock it will do the same (fill w/water that is). I would like to somehow keep water from going down there but don't have any ideas. Thanks for any ideas.