Actually, you are right, I see it all now. I own & use one, so obviously would not know how it works.
You, on the other hand, have never even seen one, and therefore are quite clearly in a much better position to make an informed assessment of the device.
In fact, I am so impressed with your almost telepathic abilities, that I am going to award you my 10/10 award, for the person most able to know everything about everything, and form a valid, strong opinion, even on devices still unseen.
In honor of your remarkeable talent, I now extend you a cordial invitation, to send me a sample of your tank water. The address is
9 Ronald Macken Place
Mairangi Bay
Auckland 1311
The water will be tested for PO4, with the Hanna. We will then be able to find out what your orthophosphate REALLY is, wether your hobby kit is REALLY accurate, and I'll even be able to tell you how often you REALLY clean your glass.
Looking forward to it. Just one thing though, I'd like the water sample to be taken from your tank under supervision of a neutral person on this site.