That isn't true at all. The pH will needs adjusting from the tap and will need periodic adjusting during use, but that all depends on how often you use it and if you spill and drinks in to during use. I check my mine from weekly to monthly depending on how often I use it. Usually every 5-10 uses. The manufacturers of hot tubs and chemicals say after every use but that is way over doing and wastes testing strips.

Basically the pH needs to be adjusted so the chlorine can do it's job. That's the jyst. There are extra chemicals beyond that but those will be used on a anually or semi-anually basis.