Don't bother artificially lowering the temperature in the leuc tank at night. The leucs won't care. As long as the ambient temperatures are bewteen 65 (or even 50 as the lowest) and 80 (try to keep it below 80 F. during the day), don't sweat the difference. Don't bother trying to control the frog tank temperatures separately from your normal house temperatues that you are comfortable in. I have been keeping dart frogs in a log school house built in 1882 in SE Idaho for seven years, keeping the indoor temperatures up in winter with a recently installed electrical heating system, plus the old wood stove when the power goes out, and in summer, when the temps rarely go above 80, open my frog tanks, put wet terry cloth towels across the tops with some ice and blow a fan acros it to cool down the tanks. But as long as I am comfortable in shirt sleeves, winter or summer, so are the dart frogs in their tanks. Consider keeping them at the same temperatures as "people without fur or sweat glands."
-----
Patty
Pahsimeroi, Idaho
4 D. auratus blue
5 D. galactonotus pumpkin orange splash back
5 D. imitator
6 D. leucomelas
4 D. pumilio Bastimentos
4 D. fantasticus
4 P. terribilis
4 D. reticulatus
4 D. castaneoticus