I know from using them for hunting that handwarmer heatpacks won't work without a supply of oxygen and that the more you give them the hotter they get (i.e., sticking them in the bottom of a rubber boot is a bad idea). Every time I've had something shipped to me the heatpacks have been cold (like stone) when they arrived, but after about 5 minutes of sitting out they get hot again. I think its unlikely they will get enough air to get to their potential temperature. So, then my question is whether or not the fact that they run out of air and stop working in tightly packed and sealed up styrofoam containers kind of defeats the purpose of using them at all? Has anyone else had the same experience? Are the heatpacks really doing anything? Are they staying warm for just long enough that they won't let your fish turn to ice cubes?
Don't mean to steal the thread, but I've been fascinated by the idea of shipping live fish and coral since I first heard it could be done.