Right, nightmare scenario. Came back from holiday to find my drain had failed some how and the main tank had overflowed.
Unfortunately I also had a big top up tank connected so not only had the main tank overflowed, it had also been diluted to 28PPT (because there was nothing coming down the drain into the sump, the ATO kept trying to top it up with RO which then got pumped into the display).
Does anybody know of a float switch I can put in the display which I can use to cut the mains power to the return pump (and ideally sound an alarm or send a text) ?
A colleague who's into his hardware hacking recommended a Sonoff Tasmota, but those are generic. I would prefer an aquarium solution that I don't have to manually code if such a thing exists.