If temps become an issue, go to home depot and buy some stryofoam, and cover the walls outside your aquarium, will work wonders.
Also your best bet is get a accurite or temp/hygro meter and just maintain the highest humidity possible, without allowing water to drip on the eggs. If your losing too much humidity, your box isnt sealed well. Or your opening too much. I'm thinking since your using water as a media, your humidty will be pretty good. Watch your eggs for wrinkiling(lack of humidity). Or lil clear windows, dots, etc.(too much droplets hittin the eggs).
Good Luck Leda![]()