Drain questions

[trouble]

first of all acrylic can it be attached to glass i thought it couldn't. or is it that when its used as material for a drain it does not need to have a good seal, it just needs to hold enough to stay in one place???? i am currently in the process of building a drain and plumbing in a sump and am tossing the idea of using acrylic or glass for my drain around. any one have any suggestions that might tip the scales acrylic/glass? and even after having previously stated that i am not going to install a herbi style drain am starting to lean towards it. my tank needs to be drilled and because it is tempered on the bottom was planning on going out the back, and since im drilling away may as well punch three holes instead of two. which kind of leads me to my next question if you were in my shoes would you extend the drain all the way to the bottom of the tank or just a small drain a few inches under the water level??which brings us back to the original question if its a box at the top made of acrylic is there any glue that will attach it to the glass and hold it in place??: pro's con's any thoughts please.