Does anyone use any of the Hanna Instruments Checkers? These small instruments are for testing a selection of water parameters. They eliminate the need for colour matching against a chart. Technically, they are known as photometers and can measure phosphate, iron, nitrite, copper, ammonia, etc. Accuracy is much better than test strips and liquid reagent tests. They are significantly more expensive than 'run of the mill' aquarium test kits. I am giving serious consideration to buying a couple of these. Any feedback would be very welcome.
I did notice that a thread was started many years ago on this very topic but the OP received no replies. I'm hoping for more success!