Water Cooling/Custom reservoir building question

Ok I've had my system water cooled for a while now, but have decided I need to make it a bit more efficient and quiet; and to do this I'm going to be creating a custom water reservoir.

Now during it's construction I'm wondering is there any particular glue, sealents, or materials I should either use or stay away from to prevent problems?

Here is my current plan: Reservoir will be stored under the computer and have a pipe like chimney thingy so that the water level in the reservoir can be the highest point in the water level (this way if I need to I can fill the system without tipping it to make the reservoir the highest point and thus the fill point) So basically it will look like a box with a tube sticking out of it (for lack of a better image)

I plan to build this most likely with 1/4" plexi glass, gluing most the edges together with Methylene Chloride so that the edges will be completely sealed.

Then having a hole in the back where I can access the pump, and as this will be lower than the water level I plan to seal this hole with a equivilent sized smaller square of plexi glued upon a large piece of plexi, which I will then seal using silicone

The system will be filled with a mixture of 19 parts water to 1 part zerex coolent/anti corrosive additive.

Anyone see any chemical reactions or worries (such as the zerex/water mixture eating the silicone or other parts of the setup)? or have any recommendations I would appretiate it.