I've never used the Phase 22 packs but I have read reviews and seen them for sale on a few different sites.
I'm not sure why it is toxic, but my experience that if you put it right on the gel pack without any barrier the water tends to cloud and the shrimp will perish. I wrap them in a plastic bag and put a little insulation between the shrimp and the breather bag and never had a problem that way. I like to use them when I'm shipping from cold to hot areas and from hot to cold since they self regulate around 72 degrees.the phase 22 seems like the ultimate product. Keeps warm only to a certain degree- so now no overheating in the box- especially when sending from one climate to another.
Keeps cold to a certain degree- so no worry about freezing.
It's almost like you could include that in every shipment as a sefguard to maximize shrimp protection.
I'm very interested and am looking into this more.
How many would be recommended for what sizes of boxes?
Why is it toxic if touching the breather?