What I tried to do here is create a new way to drain water from a pond area to under the false bottom. The reason being I wanted to sculpt the pond with Great Stuff to the shape I want. However if I did this it would prevent water from passing to under the false bottom. So what this idea does is raise the floor of pond, giving it it's own false bottom, just like the type of false bottom used in the rest of the tank.
First I took a piece of eggcrate roughly the size of the pond and melted little arch ways into the underside to allow water to flow through underneath it. You can see what I mean in the first thumbnail. I did this in both directions as you can see in the second picture.
Now what I would do is cover eggcrate with two layers of fiberglass screen, and place it on the bottom of the tank under where the pond would be. Then I would be able to use Great Stuff to form the shape of the pond to whatever form I would like. As long as I don't cover up all of eggcrate below, water would be able to pass through the screen and out under the false bottom.
The reason I came up with this, is I wanted the left side of my pond to have a verticle wall of dirt, but of course if I tried that with just substrate it would fall into the pond. With a setup like this, I could make the walls as steep as I want or as shallow as I want, and I would just silicone dirt to it. The last picture is a drawing in section of my idea to help illustrate it better.
Do you guys see any problems with this? Do you think having the drainage on the bottom would force too much dirt through the screen? I could use gravel, but I wanted dirt to make it look as natural as possible.