I have a male gecko in a 10 gallon tank with a heat pad which keeps the tank at 95f and the a day lamp, I want to setup a 20 gallon tank for two females, can I use a UVB light for the day, or does that strees out my geckos? I just want to know if they like to be dark or just normal like a 12/12 cycle?

How many females can I have in a 20 gallon tank?