Purified water is not the same as distilled especially for this use. ( I could be wrong on this - Ben is clearly the authority)
You're going to have some CC when fighting algae - don't worry about it.
Ben doesn't sell the kits but has taken the legwork out of sourcing them by recommending Amato Ind. through Amazon. Get the Taylor K-2006 as soon as you can (if you can) I find it MUCH eaisier to use / read.
Is the concentration listed on the bleach bottles? if not, presume it's less than 6%.
Don't use any special goo bleach - it just adds junk to the water you'll have to fix later.