Gypsy got me onto that stuff too.. It works really well, It works better and is more enviro friendly than the regular $20 chemical addative, And at the fraction of the cost, Sorry for the pun, but It's good knowing I'm not thowing my money down the toilet.
I put regular disinfectant in the top tank to keep odours down. A vigerous clean with hot water and diluted nappy soaker after emptying also helps. And a quick spray of olive oil keeps the seals from perishing.
Thanks again for the tips, :D