Which should I buy? TFP's recommended pool chemicals are cheap, easy, and won't unbalance your pool water.
www.troublefreepool.com
Bleach should be added to the pool by pouring slowly in front of a return jet with the pump running. You should pour slowly enough that pouring an entire jug takes more than one minute, preferably two minutes. Leave the pump running for at least 30 minutes after adding bleach.