I do not have the space heater aimed at the tank. And the temperature has been maintained at 80 all through the night. It seems that every medication has its ups and downs. the lady I talked to seemed to have a lot of knowledge and I felt my other option was to possibly further damage his labyrinth organ and she said she's used the revive in situations like mine and has seen some amazing turnarounds. I'll keep the toxicty risk in mind and will use less than the recommended amount. He seems to be doing a lot better so fingers crossed!