Neither, use bleach - the cheapest one you can find, but make sure you verify the concentration on the bottle, I found Walmarts Generic brand at 5.25% to be the most bleach for your buck, but I'm in Canada, and others may chime in and send you somewhere else for an even better deal.

I recommend you read the poolsolutions website from cover to cover, it will save you lots of $$$ and make maintenance of your pool VERY easy.

Welcome to Pool ownership!