Hi there!

I keep two RETFs and I'm no expert, learning more and more all the time thanks to my fellow Forum'ers.

12x12x18 is 10 gallons. I think that should be OK for two frogs maximum. There are different opinions on that though.

I use a Reptifogger. It's definitely enough, but I turn it on and off quite often because after a few minutes the humidity goes too high. Still it's a nice effect and I like it. I also get humidity by wet paper towels on the bottom combined with an under-tank heat pad, and a heat lamp on top.

As for lights, they do need a regular light during the day to stimulate their day/night cycle. It can be any flurorescent light, as long as it lights the tank to tell them it's time to go to sleep. 12 hours on, 12 hours off. A timer comes in handy for this, like $6 at your local hardware store.

I don't know about Reptibark. It might help with humidity but I wouldn't use it. There are many substrates you could use. The safest is a fine coconut husk, sold as "EcoEarth" or "Plantation Soil." This is the only substrate that can safely pass through a frog in case it is accidentally swallowed. I don't use it though, b/c I don't think it conducts the heat while using an under-tank heater. That's just me.

Good luck and have fun! Props to you for doing research before you acquire the frogs