We use the liquid acid on our vinyl IG pool. We add about a quart at a time. I don't pour it directly from the bottle into the pool though..I'm afraid I'll drip and burn my liner. We 1/2 fill a bucket of water, pour the acid into the bucket, then pour it into the pool at the return flow to mix it well. Then I rinse out the bucket with pool water from the end behind the return flow. Probably not necessary, but I'm paranoid

Mary