What type of top is recommended for a 20 High tank? It will be housing Pacific Chorus frogs, so it needs to have ventilation. Right now I have a small-mesh screen top on my 10 gallon, that fits flush into the top inside rim of the tank, and then with a Zilla Fresh Air screen cover over that. The mesh top would not work on it's own, as it is too light and my cats could open it. The Zilla is heavy enough, but it's mesh is too wide and the corners have gaps. I would just do 2 tops on the 20 gallon like I have now on the 10, but the 10 was a hand-me-down and I have no idea where the small-mesh top was from. It seems that a lot of people here use a set-up similar to the exoterra, but for those of you that use a regular aquarium style tank, what top do you use?