If you wanted to add a heater to your 1.5 gallon set up you could always try the Hydor Mini Aquarium Heater.
It's about 7.5 watts, small, and flat so its perfect for a small aquarium.
I've seen them offered at PetCo
Here is the link for it on the PetCo website http://www.petco.com/product/102429/Hydor-Mini-Aquarium-Heater.aspx
Hope that helped
It's about 7.5 watts, small, and flat so its perfect for a small aquarium.
I've seen them offered at PetCo
Here is the link for it on the PetCo website http://www.petco.com/product/102429/Hydor-Mini-Aquarium-Heater.aspx
Hope that helped