The advice we give is based on accurate test results. It's the whole premise of TFP. if we don't have accurate test results, the advice will likely not really be any different than the dump it in and hope it works method of the pool store. I test to see where my levels are at, check the pool calculator to see how much I need to add, and follow the maintanence advice, such as brushing amd backwashing at the appropriate time. I don't experience foam, or burning eyes, or algae. The reason everyone is so passionate (lol) about the proper kit, is because the TFP works when you follow it closely. If you need to SLAM (chances are you might if you needed to use algaecide in the first place) you need to be able to maintain a high FC, especially if your CYA is high. You also need to be able to measure FC in smaller increments to see if you've passed the OCLT. Those are the reasons we recommend the kits we do if you want our help.
As for the millions of people getting by without the kit, I'd bet about 3/4 eventually deal with ongoing problems like algae and scale, and pay the pool store big bucks to "fix" it. If only for a brief time.
As for the millions of people getting by without the kit, I'd bet about 3/4 eventually deal with ongoing problems like algae and scale, and pay the pool store big bucks to "fix" it. If only for a brief time.