Jan is right, you need a good test kit. Most of us use the kit that Ben sells at the sister site to this forum at www.poolsolutions.com. In the meantime, you can get higher readings with your kit by diluting your sample. Mix one part pool water and one part distilled water, test as usual and then multiply the result by 2. If you need to go higher, one part pool water and two parts distilled and multiply results by 3, etc.