Costs for testing vary somewhat by geographical area. As the costs of fuel rise, so do the costs of water testing service. Each company may test for different chemical levels. In Northern California, I used to pay $65 a month for weekly pH and chlorine testing and the addition of muriatic acid. I have an SWG, so no chlorine addition was necessary. I found I was having some huge swings in pH level when adding muriatic only once weekly, and they did not test for CYA. After finding the TFP website, I continued to test my water for a month until I was sure I had it, then sent the company a letter indicating their service was no longer necessary. They were actually very professional, answered my questions about equipment operation and chemical levels. TFP set me free.