Try going to a pool store and buying a couple of 5 gallon carboys of Liquid Chlorine at 12.5% (there's nifty nozzle you can get that fits the carboys that's great). Each carboy will be like adding AT LEAST 10 gallons of 6% bleach.

It will save you lots of empties and (with the nozzle) is easy to add.

You'll need to give a deposit on that carboys, but I've been recycling them for 4 years now on the original deposit!

Check pricing: to be worth it, A Carboy shouldn't cost more than 10 gallons of 6%. If it's less, it's a good price.

You need a LOT of chlorine, but at least this may make adding it all easier.