Tigerino Vet Cat Litter Additive - pH Detection

The packaging says you should compare the colour with the colour scale. This so-called colour scale is just plain yellow or blue, and if it's yellow or blue, it's different. But how different?? Acidic or alkaline? I don't expect a 100% precise result, but I wanted to know whether it's acidic or alkaline. So for my purpose, it's pointless. For the price, just detecting a difference and then still having to do extra testing is a waste of money.

Unfortunately, you can't really tell, as it changes colour—anything from "white" to yellow, green, and even blue can appear. And that's just from a single visit to the litter box by the cat. That really shouldn't happen. Personally, it just confuses me even more.