I have a 70,000 litre pool with a fairly ancient RolaChem RC25-7 controller injecting acid and chlorine from 20 l containers.
I have finally accepted that the ORP and PH sensors are dead. pH is not such an issue as I have an instrument quality meter and the pH is pretty stable. I do need to replace the ORP sensor however.
A call to the local agent went like this:
"Gidday, I'm after a replacement ORP sensor for a RolaChem controller"
"one moment please... -is that the RC-9?"
"No, it's an older one, but I'm sure it will be compatible if it has a BNC connector"
"OK. That'll be $640"
"Ahh, no sorry, I just need the sensor, not the whole setup"
"That's the price of the sensor. The units are $3500...."
Now I see Ebay has aftermarket ORP sensors for $30. At that price I could afford to replace them every year. I'm assuming that being based on a cell potential, all ORP sensors are basically the same.
Does anyone have a comment or experiences?