pH, Free Chlorine and Total Alkalinity Sensors

pH is no problem. FC and TA are another issue. If you are not using CYA in the hot tube you can use an ORP probe to measure the free chlorine. To the best of my knowledge there are no TA probes, most TA instrument rely on titration. In any case any of these options are not cheap. The pH and ORP probes will probably run $1000 to $1500 each.

Awesome thanks! I'm thinking I should be able to infer alkalinity based on pH changes after adding acid and corroborating with some manual measurements at the beginning. Good enough for what I'm using it for anyways.

Do you happen to know of any good brands for pH and chlorine?

Thanks again!

Here I found many topics regarding pH measurement. This link is for common mistakes, but it is linked to many devices, which I believe was your question. I saw another article in the site on how to change voltage signals into Ampers, but I cannot find it. I think if you directly ask to these guys they might help: