twister, I don't know what product you are using for water. I used a clear, water-based, urethane for my stream. To prevent the problem you are having I did most of of my scenery first, then painted the stream-bed with the urethane to seal it. After the urethane dried and sealed the stream-bed I could pour in thin layers of the urethane to fill in my stream. After the stream is done I will go back and place the plants along the banks of the stream. I would think you should be able to do the same with whatever product you are using, put a thin coat down to seal the area first, and after its dry fill your pond with more. Most products recommend thin layers like 1/16th to 1/8th of an inch, if you pour it too thick it may not dry properly and stay a milky color for a very long time.