These are gimmicks. Typical of most products like this - they take a scientific principal that sounds reasonable and apply it to a situation where it will not do any good. Then they get to either sell you the product over and over again or some consumable related to the product. All the while they keep you hooked by playing on your anxieties over a catastrophe that will never happen. Or you get the standard Facebook advice that some random person posts about how their grandmother’s mailman’s sister-in-law’s boyfriend is a college professor who “studies” this stuff “in-depth” and absolutely advises everyone to get one because it’s based on “science” and, hey, it can’t hurt, right?
Save your money, buy a good test kit, keep your water properly balanced and your pool will be fine.