Well increasing the temps kicks in the snakes own immune system plus if you are using antibiotics like Fortaz or Baytril then the temp increase will also speed up their metabolism which helps the antibiotics. Anytime a reptile has a RI, you should raise the temp. Also, you definitely want to get a culture at the minimum from the vet to find out if its bacterial, fungal or viral. My beardie had a bacterial RI which took about a month to cure. None of my snakes got it but I also Chlorhexadined everything and always washed my hands inbetween anything to do with my animals. Too bad about your collection all getting it. Was it an airborne bacteria or fungus or something? Mine had Enterobacter which the vet told me is the most common kind which is found on pretty much everything but only really strikes when an animals immune system is suppressed. And is really only transferred from fecal to oral like if it an animal pooped on the floor and you just wiped it up but didn't sanitize the spot and some other animal licked that spot. Anyways, sorry to hear that. Sucks to lose a whole collection