Plumbing the drain to the filter

[SquishyFish]

Okay..the hole is dug (mostly) and I am finishing "sculpting" it. Which, by the way, is more work than I would have ever imagined it being. The pond liner is purchased and waiting to be installed. What I am trying to work out now, is how to plum the drain for the pond into my filter.

What I had originally planned to do, until I can afford a real filter, is to take the pond pump that I used for my 120 reef tank and use it to run the water fall. The idea was to have a submerged [acronym:cac92df43a="Plastic pipe"]pvc[/acronym:cac92df43a] pipe that allowed the water to flow into a rubber maid tub. From there, I would use a DAS filter from my tank (this thing is LARGE) to scrub the water. The pond pump would then push the water up to the water fall. The upper resivoir would be made from concrete that channels the water to several different "fall" points on the rock wall.
Here are the 2 problems. Can I actually have a submerged pipe or will the water just fill to that point and no higher. 2ndly....if the pipe is submerged can I simply cut a + into the liner, clamp it with a hose clamp (maybe a use a little [acronym:cac92df43a="Plastic pipe"]pvc[/acronym:cac92df43a] glue) on the dry side of the liner....then silicone the wet side....or would this leak?