I think my 5 gal is cursed or something, lol.
I went and returned the Hydor Theo and got a 25 w Stealth heater from Marineland-the only type they had left.
The tank it only at 74 degrees! I'm starting to wonder if I'm doing something wrong, though how can you mess up a heater? I let it sit there for about 10 minutes, then plugged it in. I did this last night btw, so it's been more than 12 hours since.
So far Renard doesn't seem to have a problem with the temperature. I was floating him in the 10 gal last night, but given the condition of the fish I was iffy to actually put him in. I put him in the 5 gal today and he seems to be loving his new home! Checing out every nook and cranny, and he's so tiny in there!