You really need to get your own kit so you won't have to rely on the pool store. And, with high CYA, you're going to have to run high chlorine levels as Janet mentioned. You need a kit that can test as high as you're going to need and the K-2006 kit will do that. If you haven't already done so, please read the Best Guess Chlorine Chart in Janet's signature above. With a high CYA and chlorine at only 3ppm, you are going to have algae problems. (It is actually very likely that you really have CYA over 100 since that test can't differentiate values past that.)