Monitoring pH levels... how ?

[Adrian Brentnall]

HI Folks Or domestic water supply is from a private borehole. To reach the borehole, the water's percolated through a peat-laden Irish hillside - so it naturally pretty acidic. Untreated, it attacks the copper in the hot-water tank and we get a nice turquoise-colour in all the hot water.

So - we have a commercial metering/dosing system that injects an alkali into the water as it's pumped up from the ground - to bring it back to pH7.

All's well - until the 5-litre container of alkali runs out (every 4 months or so). The dosing box recognises that the alkali's out - and lights a helpful little light. Dosing box is tucked away at the back of the mower shed... so the light goes unnoticed. The dosing stops (though the pump will occasionally pulse enough times to generate an airlock in the dosing feed pipe.

Next thing you know - it's blue bath-water again - which takes a week or so to clear, as the hot water tank is fed from a big cold-water storage tank in the loft - and the 'neutral' water has to work its way through the system. Said airlock also has an effect - requiring kneeling in the back of the shed, manually pulsing the pump while loosening the pipe-unions and getting strong alkali up your sleeves...

So - ideally - it'd be good to have a monitoring system that says 'pH too acidic' - and - "dosing alkali about to run out".

Any bright ideas, please ??

Thanks Adrian

[Scott M]

Open box, remove light, extend wires to house (or at least outside of shed), reattach light.

(Or similar variants.)

[charles]

How about a security camera looking at the light on the dosing box?

[Nightjar]

Can you not top up the alkali every month?

Colin Bignell

[Adrian C]

Fit a Kalaxon ...

[F Murtz]

Wire up a fire alarm bell to the indicator through a suitable interface?

[Davey]

I know that commercial pH meters that do exactly this are available, I've used them at work. No idea what they cost, though, that was somebody else's worry! Google?

How about:

[GB]

Does the helpful light come on *before* the alkali runs out completely? If so, you definitely want one of the excellent solutions given here that monitors the helpful light, rather than a pH meter. The pH meter only notifies you after the alkali has run out.

As Colin suggested, surely the lowest cost solution is just to diarise to top up the alkali before it runs out?

[dennis]

fit a reverse osmosis filter (+ ion exchange resin, if needed) so you don't need the alkali dosing.

[mogga]

Write it on the calendar to check a couple of weeks before you expect it to run out. If your water use is fairly constant through the year this should be fairly easy.

[John Rumm]

Microswitch under the container - sprung to enable once the container is down to the last half litre...

[Onetap]

Or a float switch in the container. Or extend the warning lamp thing, via a relay if necessary, as suggested above.

[Huge]

+1

[Rick Hughes]

write a routine in Raspberry Pi to monitor the light, then once triggered, trigger a pair on contacts to attached WiFi on a Wifi transmitter ... which send signal to router .... set up port scanning ... to trigger alarm. Which sends signal to ISP which in turn sends you SMS txt to top up.

Alternatively - extend the light ... or change light to a buzzer.

[John Rumm]

Yup that could work...

I was assuming the lamp indicated "empty", rather than the more useful "nearly empty"

[Bill]

+2

It seems to be the simplest, quickest reacting and most accurate answer.

Either rewire it back to the house or fit a suitable sounder to it.

[The Other Mike]

Get rid of all the copper and replace with stainless...or lead

[Adrian Brentnall]

Thanks for the suggestion. I should have said that the light's a small led - and probably not visible in daylight. Also don't really want to start hacking about with the electronics of the dosing box. The led indicates a bit 'after the event' - what's really needed is a 'you're about to run out of alkali'-indicator....

[Adrian Brentnall]

Same as my reply to Scott (above).... Can't see the led driver being very happy with driving a klaxon - and can't see swmbo being very happy with it either!

[Adrian Brentnall]

Still doesn't really do the 'about to run out' warning