What do you suggest for a tube-style 25W heater for a 5.5g aquarium? This might sound silly, but I want a tube because my betta likes sleeping behind the current heater on the top suction cup. As much as I like the Cobalt Neo-Therm, it doesn't look like it has enough space for him to do that.
Here are the models I've found that look good:
Jager - I would have already ordered one, but have read that their quality has gone down recently. Also, some people apparently have difficulty calibrating it. What do you think?
Cobalt Accu-Therm - Cobalt seems to have a good reputation (aside from some defective larger Neo-Therms a while back), but I don't see much feedback on the Accu-Therm.
Hydor Theo - It seems like a popular budget choice, but I get the impression that it isn't quite the quality of the other two.
I'm replacing the current heater, a Pet Supplies Plus model, because white slime has started accumulating on the rubber end pieces. I did my best to clean it off, but it came back within a couple of days. The slime isn't anywhere else, so I think it's just this material.