I have read from somewhere, I thought on this site, that other folks do it to prevent algae from growing and stopping up the water lines. I also saw on one of those survivor type shows where they put bleach in their water to kill bacterias and stuff so I figured with such a small amount it should be safe.

The temperature is an issue but that is only the last week to 10 days that it has been colder, these issues have been going since I started.

I did purchase medium females the last time I went, about 3 weeks ago. Hoping the younger females will last longer and be in better health.

Also something I thought was strange, when I placed my order he said he didn't have ANY females bigger than small, which made me think they must have died for whatever reason, i.e. bad health / environmental issues, but of course I have nothing to base it on other than my other purchased rats dieing for no apparent reason.