great DIY postmandave!

I have 8 plants about 2-3 weeks from harvest and they're starting to smell. I'm trying to put together your odor neutralizer and have everything together except I'm having trouble finding hydrogel in the US (upstate NY). I was hoping someone could lead me in the right direction. Maybe there's a brand name I should be looking for instead of just hydrogel? Any help would be appreciated, thanks.