I'm too growing in a rubbermaid with 300watts of true cfl lighting, computer fans for intake and outtake are a must. I have 2 80mm fans in and 2 80mm fans out, plus I supplement with c02. With this setup my temps range from 70-83. You can wire these computer fans up to a 12v ac/dc adapter which...
If you haven't done so already, you should invest in a good digital PH meter that will run you about $80. The cheaper meters are almost always off by crazy amounts and should not be trusted.
I too just went through some bad root rot which onset early on in flowering. I've been nursing the plant along under my 600watt hps and even been supplementing with uvb. Of course yields will be reduced, but a badly infested crop can usually still live with proper care. I'm now about a week away...
Heres a pic of my supercropped afgoo clone at 3 week flower, but is now about 3 weeks from harvest at day 40. I've just been nursing it along with root rot coming on at about the second week of flower.
I recommend adding some beneficial bacteria such as General Hydroponics Subculture or AN piranha/tarantula to create a healthier environment for your roots. Doing so will allow your plant to better absorb nutrients and lessen the chance of developing biological issues such as root rot.
-John