I only started using Purigen this week but am really impressed with how well it brought down N in the seahorse tank.
To be honest for less than $30 a year I can buy enough for my 215g tank. Even if I don't regenerate it and just buy new that's a really good deal compared to the $200 worth of pellets I burned through last year.
It's supposed to get really noticeably brown and on average lasts about 6 month I think:
http://www.seachem.net/Products/prod...s/Purigen.html

I bought a small bag already in a filter bag from you guys and didn't notice any smell but I also have a big container that came without a filterbag and when I bagged it for the big tank I noticed it smelled 'funny' straight out of the bottle so it may not have much to do with the bleach.