The holy grail - ORP!

I've wanted to try and will at some point, try one of their pH pens. I've used their top of the line handhelds (6P variants) for about 15 years now, and I think they make the best handheld pH, ORP, and conductivity meters you can buy. Mine does all that plus TDS/salinity. The feedback I've had on the pH pens like this one have been very good from other industry veterans I trust. As for ORP, Its very difficult to get consistent readings on one versus true comparison for FC, much less two. But, if I were looking for a trustworthy hand held pH or ORP meter, I would certainly give the MyronL pens a try. Just FYI, Taylor Technologies has the best price on them, but I can't remember if they carry the ORP version. They should, as only the log curve for the calculation is different for ORP, as they both read and measure the exact same way. This is generally true for most all ORP and pH probes.

If you want to go all out, they make a Pool Specific version of the 6P that even does saturation index calculations, and it only runs about $1300. :)

Here it is-POOLPRO™ Professional Water Analysis for Pools and Spas
 
They also make the Ultrapen PT4™ which will measure Free Chlorine (FC) "Equivalent", but it apparently does so by measuring the ORP and the pH so I suspect it does not take CYA into account at all so will likely not be accurate in pools with CYA.

Taylor sells the PT1, PT2, and PT3.

If the pH pen is accurate, then it can be useful especially for those who are color blind or have a hard time reading the colors on the pH test. ORP, on the other hand, is a lot less useful since it tends to not be nearly as accurate or consistent. ORP values vary from different manufacturers and even different models. See this post that showed the kind of fairly broad variation you can expect from ORP sensors and where even measuring the same water, 30 out of 130 pools showed 100 mV or greater differences between two sensors. They are most useful for process control using a setpoint you determine by other means such as determining FC from a FAS-DPD chlorine test kit. Even then, one must recheck periodically and adjust the setpoint accordingly.
 
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