Chest Freezer Into Fermentor Question

[KijanaKiume]

Hey yall quick question. I'm building up my stuff to get back into brewing. I'm going to use and old freezer with dual controller for my fermentor. What do yall use as a heater in this scenario?

 

[Konadog]

Depending on what your using to ferment in, I use one of these on carboys, and recently on my BrewBucket.
https://www.homebrewing.org/Carboy-Heater_p_1732.html?AffId=160