I have a 48" reptile terrarium that I'd like to convert to a frog vivarium. It's not that the terrarium isn't watertight, it is. It previously housed a dwarf monitor, so it's had wet dirt and mud in it before. I think what it is is that the glass is too thin to support the weight of the water should you fill it to the top. The glass is about 1/4" thick, so how much water would be safe to put in it? Remember, right now it has 5" of dirt.