pour it into the skimmer, run the pump for the first 24 to 48 hours and DO NOT CLEAN OR BACKWASH YOUR FILTER FOR ONE WEEK! The CYA will collect in the filter and takes about a week to slowly dissolve. With the Aquarite you want 60-80 ppm CYA so for a 13,000 pool that would be 8 lbs to get you to just under 80 ppm. Don't overdose and test the level about a week after you add it. You might want to add 7 lbs, wait a week and test, then add more if needed. & lbs will certainly get you in range. I am assuming that there is NO CYA in your water right now from any pucks that might have been used before your SWG went online. If stabilzied chlorine was used in your pool you need to test the CYA level before adding any so you don't overdose! The amonts I gave you are for 0 ppm CYA initially!