Hasn't even arrived at my doorstep yet. As mentioned in another thread, I ordered it online thinking that it was the right product to treat my scale condition, and then found out that it is not compatible with my biguanide pool. I paid $18.99 per quart but would be willing to sell it for less. I thought the pool store I always dealt with would be willing to swap for a different chemical, but they aren't since I didn't buy it from them. Having been close to a 30-year customer of theirs, I thought that was being a bit tough actually. So if anyone is interested let me know. The stuff will obviously be unopened and fresh off the FedEx truck!