Carefresh is extremely dusty unless you screen-sift it first. I tried it ONCE and all of my rats had alot of problems with it. Itching, sneezing, etc. I use the shredded aspen from TSC now and it works great. You can get a 5.5cu. ft. bag for $8.65(or something close to that). I would get rid of the carefresh and find a good source for aspen. Check around at local feed stores.

It would also help to get each of them a same-sex cage buddy(meaning get another male and female pair and put them with their same-sex counterparts). That would reduce their stress.