I'm trying to keep the design at a low price point, for probes too. I think the ph probes I have been using are £10 each. or less. the ORP probe I bought a few years ago and was much more expensive. No conditioning op-amp provided. Incidentally I am also designing an arduino control for a variable frequency device to power a standard three phase pool pump. Much much cheaper than buying a variable speed pump
Another option which looks more on the industrial side is this.
I'd have thought the need for electrical isolation could be circumvented by dropping a ground probe into the water being measured. That's my plan.
Outrageously priced at 60$. Component cost looks like a couple of dollars disregarding the connectors.
the pH is corrected for so we are testing for ORP when the pH is balanced.
Or am i.missing something?
ORP sensors (by my reading) are not tricky to use.