As you'll recall, the heaters in Hambase Alpha broke toward the end of it's use. The problem was I had exposed connectors on the outside of the hull that the USB cords plugged into to supply power. Water got into the space inside the connectors and rusted them to the point that power was no longer being delivered (It isn't salt water, so there wasn't a significant short and the heaters worked fine until rust set in)
Since I had a bunch more heater pads laying around (these are cheap) I decided to finally get around to adding a pair of them to Hamlab. I never left a hamster in this habitat for any length of time before because it didn't have heaters. I didn't bother adding any because why have any of them live here when they could enjoy the more spacious, wheel equipped Hambase? But with Hambase undergoing refurbishment, I'd like to have one hab fully equipped to support a hamsternaut comfortably. I plan to buy a new set of hambros soon. This won't hold three or even two, it's just enough space for one of them, for durations of 1-3 days (as there is no wheel) this should at least get me back into the business of underwater hamster shenanigans, and motivate me to fix up Hambase Alpha faster.
What it needs is to have the two little heating pads (like those in Hamlab) removed, and replaced with a Reptitherm 110v heater pad that covers nearly the whole floor. This way, three hams don't have to fight over two small heating pads, each only big enough for one of them. Even when the heaters in Hambase worked, that was a problem. Sufficient, even heating is an absolute priority for submerged small animal habitats. They aren't big animals, they lose heat easily and have fast metabolisms. They originally lived in deserts, so they need to be kept warm. Even with an aquarium water heater, the temp your fish like is still uncomfortably cold to a small mammal. Anyone working on their own such habs should take note, if it hasn't got a heater, it isn't fit for occupation for longer than a few minutes. If it hasn't got a wheel, a few days is the maximum 'mission duration' I recommend, as they need the exercise+stimulation.