Heater for 2.5gal Reef

[User]

Hello everyone! The title pretty much says it all.

What is a good/reliable heater for a 2.5gal tank? The smaller the better as well.

Thanks!

 

[Kosamamama]

I bought a 25w on amazon. It keeps my tank at 73.8 on its lowest setting. Fluval sells a small flat heater intended for their 2g spec tank that works well too!