It is possible to get by with a Walmart test kit. I've been doing it for the last 15 months. Chlorine and pH results aren't super accurate but close enough. I've had my water tested enough times by several different pool stores so that even with their sometimes screwy results, you can eventually throw out the obvious errors and have a reasonably good idea of your Alk, CYA and Hardness levels. It's then a fairly simple matter of remembering that as long as you are not having to drain or fill a lot of water, your levels will remain in a reasonable range. ie: If you have good reason to believe that your CYA level is ~40 ppm and you haven't added any, you can afford to roll your eyes at the next pool store clerk who tells you it's 80 ppm. I just decided to dispense with pool stores entirely and buy Ben's kit so I know exactly what's what all of the time.