Help! Heating ideas for 15-gallon glass bottle habitat...

[CallaLily]

It looks very pretty, but I'm with SG on this one. It's too small and the substrate is too shallow to house anything more than a couple of the tiniest crabs safely and then only for a short time. They will very quickly outgrow this space. (IMO, a 10 gallon is also too small for the same reasons)

[Andre0170]

I appreciate the comments. This particular bottle is providing over six inches of substrate and 55 more square inches of surface area than their old tank. The unit holds 15 gallons - Isn't the rule of thumb 5 gallons per crab? Temps and humidity are more easily consistent too. It's definitely an improvement over the old tank, which definitely had grown too small. So I feel good about that. But, yea, as they grow, I'll move to a bigger unit.