Green pool, advice from local pool store?

[kelemvor]

You need to get your pool to shock level and keep it there until you don't lose more than 1ppm FC overnight. I like my pool store guys because I think they've given me good advice in the past (they have told me the exact same things I've read on this forum), but I really question adding CYA before shocking as well as throwing Sodium Bromide (mustard eliminator) into your chlorine based pool. Getting mustard eliminator back out of your pool once you add it can be real tough from what I've read. I'd avoid that stuff like the plague, personally.

At 15ppm CYA you need to reach 12ppm or higher FC to shock the pool. In 34k gallons you'll need about 7 gallons of regular 6% bleach to get there. Most folks find grocery store bleach cheapest, but my local pool store sells 10.5% for less overall (about half the price) than I can find 6% bleach for, so I use that. If you use 10.5% you only need 4 gallons.

Also, you might really want to consider getting a good test kit and testing the water yourself. It's probably the best investment a pool owner can make, especially when fighting algae like this. The Taylor K-2006 is the kit to get, and this site has links to order it here: http://poolsolutions.com/testkit-order-links.html. You can order it elsewhere, just make sure not to get the K-2005 by mistake.

The numbers I gave you above were based on the "best guess chlorine chart" (to figure out your target FC given your CYA of 15) and the pool calculator (to figure out how much to add given your water volume).