HCA: Hermit Crab Association

Thinking about getting these for what I think is a fungus gnat problem in my 55g crabitat.
http://www.evergreengrowers.com/fungus- ... aspis.html

I have reptile tanks in my room too, is it possible these mites could make their way from tank to tank on there own?

Yes, and that's a good thing. In fact, you get sooo much I would put a bit in each tank and clear up your whole zoo!

I've always read mites are bad for reptiles, so I'm nervous. ^^;

these mites only eat other mites.

There are thousands of species of mites out there. Specific ones can infest reptiles, but they're certain species that only that can only prey on reptiles. The type of 'good' mite that is recommend for 'bad' mite outbreaks for hermits will also eat the 'bad' mites that infest reptiles.