you could do what Honda said about the heat packs.
I would use a heater or heat source of some sort. A heater would be good because you can set it for the temp you dont want it to go below. That way you dont have to worry that the water is too cool and you dont have to worry that heat packs will get it too hot.
I would use a heater or heat source of some sort. A heater would be good because you can set it for the temp you dont want it to go below. That way you dont have to worry that the water is too cool and you dont have to worry that heat packs will get it too hot.

