Usually, we recommend that folks purchase the K2006 kit, which allows you to measure CYA (stabilizer) levels, and accurately measure chlorine levels above 5 ppm. There is a link, to various kits available from Amazon -- usually, the preferred seller there is Amato.

Alternatively, you can take your water to a dealer. The problem is that they often use test strips, and the CYA test is the worst of a bad lot -- we often refer to test strips as "guess strips" because they are so vague in their results.

What sort of pool do you have?