Turning a doser off if ph greater than

[Clownfishy]

I think I have this code right but would someone be so kind to double check this -

Fallback ON
If pH > 8.25 Then OFF
If pH < 8.25 Then ON
If Time 09:00 to 17:00 Then ON

This outlet controls a 2 head Jebao doser which doses NOPOX during the day and kalkwasser at night. To ensure my pH does not continually climb during the night, I want to cut the power to the doser off if the pH rises above 8.25. I also want to ensure that it comes back on again between 9am-5pm where the doser is programmed to only dose NOPOX throughout the day and no kalkwasser.

Many thanks for any help

[ryeguyy84]

That is only going to run from 9-5. Is that what you're looking for?

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[anit77]

I may be wrong but, think that will work. I believe you should add a Set On to it as well.

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[RussM]

Your concept is OK but I would lower the threshold for the unit to kick on during the non-daytime period.

Fallback ON
If pH > 8.25 Then OFF
If pH < 8.18 Then ON
If Time 09:00 to 17:00 Then ON

This prevents the addition of kalk if the pH is relatively close the your high threshold of 8.25; it won’t start until the pH has dropped several hundredths. It also adds hysteresis so that if the pH hovers at 8.25-8.26, the output will not bounce on and off frequently.

[Clownfishy]

@RussM, so this will only go off if pH is over 8.25 but once off, will stay off until ph drops to 8.18 when it will turn on. All other times the outlet will stay on?

[zombie]

@RussM, so this will only go off if pH is over 8.25 but once off, will stay off until ph drops to 8.18 when it will turn on. All other times the outlet will stay on?

Yep

You might be an engineer if...You have no life and can prove it mathematically.

[Clownfishy]

Many thanks for everyone's help, really appreciate it :-)

[Clownfishy]

The outlet went off at 17:01 but the pH was in range for it to be on. Is there an order I need to set these as I the only reason I put the time parameters is if the pH is above 8.25 during those times, I still want the outlet on as the Doser is not set to dose during those times?

[zombie]

Then I would use this

Fallback ON
Set ON
If pH > 8.25 Then OFF
If Time 09:00 to 17:00 Then ON
Min Time 010:00 Then OFF





You might be an engineer if...You have no life and can prove it mathematically.

[Clownfishy]

Just tested this by changing the pH value lower to force it to switch off. The changed the value to greater than 8.25 saved it and it did not come back on. As soon as I removed the line stating the time saved it, it came back in. It does not seem to like the the time parameter once the greater than statement from off to on

- - - Updated - - -

I need to be able to use some "or" and "and" commands but I don't think that is possible is it?

[zombie]

Just tested this by changing the pH value lower to force it to switch off. The changed the value to greater than 8.25 saved it and it did not come back on. As soon as I removed the line stating the time saved it, it came back in. It does not seem to like the the time parameter once the greater than statement from off to on

- - - Updated - - -

I need to be able to use some "or" and "and" commands but I don't think that is possible is it?

You just didn't wait long enough. The min time forces it off for 10 minutes.

You might be an engineer if...You have no life and can prove it mathematically.

[Clownfishy]

DOH!!! Just tested it again and it works if I just wait as stated :-). Thank you for your help :-)