Okay, well if you REALLY want to clean it and kill EVERY possible thing that's in there, here's a recommended bleaching method:
Fill up the tank with 20 parts of scalding hot water, 1 part clorox bleach. Let sit for 20 minutes. Dump out.
Fill back up with scalding hot water and LOOOOTS of dechlorinator. Let this sit for oh, like 5 minutes or so. Dump it out - then rinse it about 40 more times, everywhere.
THEN... go turn on your shower just as hot as it will go.
Set the tank under the shower for 20-30 minutes or until you're satisfied that it's clean.
OR, if that whole business makes you nervous, do the exact same procedure, except with hot water and LOTS of salt. And you can skip the dechlorinator level. Just make sure you rinse, rinse rinse it.
Hmm - after reading your coments, if it's just really dirty I'd give it a good scrubbing with some really hot water and salt, and let that soak. That should do it.
