Tragic day for my snakes.

[Aste88]

Sorry I guess I haven't been clear. Those are analog dimmer, they might be a good idea after the relay but that's not what I'm referring to. I'm talking about digital ones that can be controlled trough the GPIO and substitute the relays. Good thermostat like the herpstat aren't on-off and are able to keep the temperature more constant. They do that by either dimming (not sure how) or using a proportional function to calculate when turn on or off the heat (like sending pulses).

Since you're setting up such a good system I'd suggest going for a proportional relay.

Edit: not sure if I'm looking at them right but they seem expensive, maybe you can implement it software side like this https://learn.adafruit.com/sous-vide...rtional-output