Hi Sarah..
I have actually have no idea of your type of set up you have or what your white lipped tree frogs need but any set up can be tuned just for your frogs.. Your ambient temperature (room temperature) also needs to be considered.. Honestly I have 4 red eyed tree frogs in a 24x18x24 exo terra. I dont have any type of heater in their.. Now I do have a light on them which is just a cheap 100w light bulb that heats the tank up.. I put a thermometer as far away from the light as possible which gives me a better reading. I also have to have 2 different parts of my tank a different temperature usually high and low. So that when the frogs get hot they can go to the bottom where its cool. You asked about wattage and brand names. How many gallons of water do you have for the heater to sit in.. What is your tank dimensions and how much water is at the bottom.. You can then figure out how many gallons or what of water you have.. Then you can just get a heater that fits that size.. If you only have 8 gallons of water you could get a 10 gallon heater or even a 15 gallon heater. Honestly heaters are just like light bulbs they never last forever. I just use cheap walmart ones because I will have to replace them again sooner or later.