25 hr or 10 hr heat-pack for small styro box overnight???


New member
For overnight shipping of only one or two bags with ricordea, mushrooms, etc, would a 25 hour heat pack overheat a small styro box (inside dimensions 10"x10"x10" and styrofoam is about 1.5" thick)? The heat pack says that it get ups to 135-155 degrees F, so in such a small volume I would hate for things to get too hot right off the bat. I would be shipping from Florida to colder climates, so it is more important that the heat is still there after 24 hours. My other alternative is the standard 10 hour heat packs which are about half to one third the size. Seems more realistic for the size of these small boxes, but if they are going to burn out quick, then they won't be of much use.

I am hypothesizing that in such a small air space, oxygen in the box is a limiting factor to how hot and how fast these packs will oxidize, so that could mean that the 10 hour pack could work longer, or that the 25 hour pack would burn cooler and more controlled.

Any thoughts on the science of overnight shipping of corals? Any tips with regards to which service is the most reliable for arriving alive overnight (FedEx, UPS, DHL) would be helpful too.