I would stick with glass. Silicon would give you the secure watertight seal you are wanting. You will first want to remove all silicon and silicon residue from the seams you cur free on the tank. Then run a nice thick bead of silicon on the new glass and lay it in place. Let it cure for 48 hours or longer. Fill with water to your max projected water height and let sit for 48 hours to test for leaks.


I am not sure on adding a door to that side. Without the proper frame or glass on all sides the remaining walls will start to flex and fall.

A picture would be very helpful.