First thing you need to know is the type of glass you're going to need. It needs to be relatively untreated. That is, if it breaks, you want it to crack instead of shatter. It also needs to have the appropriate thickness to withstand the weight of the water. A tank with dimensions 36''x15''x18'' (42 gallons) needs to have 2 mm thick glass. I used an online calculator that can be found here:
http://www.theaquatools.com/building-your-aquarium
The individual pieces of glass can be connected and sealed with silicone. From what I've read, the silicone sealant shouldn't have any additives to control fungus and other gross stuff because that can be harmful to your tank fauna (aka turtle).
That be said, I've made a list of the necessary components:
-4 18''x36'' pieces of plate glass (Home Depot)-$ 39.92
-finished wood for base- robbing dad's workshop
-GE Silicone I 9.8-oz. Clear Window and Door Caulk (still have to check ingredients)(Home Depot)- $5.21
The whole project should cost $45.15, and considering that a commercial 40 gallon is around 100 dollars, it seems like a pretty good deal.
If you know anything about the silicone sealant, please reply with the details.


