A reptile tank should be at least as long as the adult animal will grow, and a minimum of half the adult length for the depth. Height is dependent on the behaviour of the reptile - whether its arboreal or whatever.
The pH of a liquid can be measured in a number of different ways, using liquid, paper or electronic testers. The most common ways to test aquarium water is with either liquid or paper test kits. pH...
find the area of your glass tank then find the volume of your tank then multiply it by the density of water, that should give you mass, since density=mass/volume