Kalkwasser dosing shut off with high phtrol

Discussion in 'GHL Advanced Technology' started by Mortie31, Mar 20, 2017.

  1. Mortie31

    Mortie31 Well-Known Member

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    hi all
    Just wondering the best way to do this, I run a kalkstirrer with a standalone dosing pump, I would like the dosing pump to switch off if the ph rises to 8.5, I cannot work out how to do this as I don't want to use 2 point control as I don't want the dosing controlling just switching off in an overdose situation.
    Cheers Paul
     
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  2. Bob Stohrer

    Bob Stohrer Well-Known Member

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    I set something similar, except I only dose (actually ATO) at night when pH tends to drop.

    Instead of the 2 point for the controlling ph probe, you could use either the "pulse variable" or "pause variable". It really depends on your doser rate versus water volume, location of doser drip versus pH probe. I had to do by trial and error by starting with a short pulse and a longer pause. I ended up with a 7 second pulse and a 450 second pause to keep pH at 8.17-8.20 most of the night.

    Some others may have some alternate suggestions. Post any additional details and/or followup questions you have.

    Hope that helps, Bob
     
  3. Mortie31

    Mortie31 Well-Known Member

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    Thanks, I have the dosing volumes and frequency sorted through a timer doser, I really don't want to mess with that, I simply need a program to turn the doser off if there's an overdose.
     
  4. Bob Stohrer

    Bob Stohrer Well-Known Member

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    OK, I understand. Is the doser controlled (on/off) by a socket via the outlet?
     
  5. Bob Stohrer

    Bob Stohrer Well-Known Member

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    Or via a schedule on the doser tab like shown below?

    upload_2017-3-20_12-44-46.png
     
  6. Mortie31

    Mortie31 Well-Known Member

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    Hi Bob, currently I have the outlet for the doser set to always on.
     
  7. Bob Stohrer

    Bob Stohrer Well-Known Member

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    So you want the outlet off at pH greater than 8.5? Correct?

    Bob
     
  8. Mortie31

    Mortie31 Well-Known Member

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    Yes mate
     
  9. Mortie31

    Mortie31 Well-Known Member

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    The simplest things seem so difficult I've looked at PL and using alarm, but the alarm ph trigger has a minimum of 0.5ph from set point, which is to high. I'm sure I'm missing something really obvious....
     
  10. Bob Stohrer

    Bob Stohrer Well-Known Member

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    First set your pH probe 1 (or a virtual probe 2, or 3, etc.) nominal value to 8.5

    Set the socket that controls the doser as shown below. I used Switch channel 8 for the example.

    upload_2017-3-20_13-34-13.png

    That will shut the dosser off at or above pH 8.5.

    Is that what you are after? How are you controlling the timing and volume of the doser?

    Bob
     
  11. Bob Stohrer

    Bob Stohrer Well-Known Member

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    I didn't see this post before replying. I don't think the General Alarm is what you are after for a shut off. If you give me a bit more info, I'm sure we can get it to work. It's been working on my system for a week now.
     
  12. Mortie31

    Mortie31 Well-Known Member

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    Thanks Bob, I've tried this way and used 8.3 with a histresis of 0.4which according to the manual should switch on and off at 8.3 and 8.5 but I've found the socket switched off when the ph is 8.1, which is the last thing I want as I don't want the dosing interfered with unless in overdose. In your example in the ph probe settings what do you set the hysteresis at?
     
  13. Bob Stohrer

    Bob Stohrer Well-Known Member

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    I think a nominal value of 8.3 with a 0.4 hysteresis should switch off at 8.3, then back on when at 8.1 when you set pH-value increase on the socket or in PL. If you set your nominal to 8.5, it should switch off at 8.5 and back on at 8.3 when you set pH-value increase. My pH probe 1 settings are below.

    upload_2017-3-20_14-24-44.png

    I set S12 below to pH-value increase and at probe value = 8.18, S12 is on. It will shut off at 8.2, then back on at 8.175.

    upload_2017-3-20_14-32-46.png

    I just changed my nominal value to 8.17 and S12 shut off. So, it seems to work the way I described it.

    I hope that helps, Bob
     
  14. Mortie31

    Mortie31 Well-Known Member

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    Thank you yes it does work to switch off at the high histeresis point however it won't switch back on until the low point is reached and this could take hours and hence mess my dosing up. The histeresis works on a +\- around the nominal setting therefore 8.5with a hysteresis of 0.4 switches at 8.3and 8.7ph, this is what I've tried from the programming manual example. But the issue of being off until the low point is reached is why I was after just an emergency off situation to prevent a catastrophic overdose. My ph runs between 8.1 and 8.25 so a off point of 8.5 will never be reached unless something has broken, hence why I want it to turn off only if that point is reached.
    Thanks for trying to help.
     
  15. Bob Stohrer

    Bob Stohrer Well-Known Member

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    I wish they had a hysteresis option of zero! What if you set your hysteresis to 0.05 (the minimum). If you got to 8.5, the doser would shut off and then back on again at 8.475? You would hover between those 2 points until you rectified the situation. I chose the tight hysteresis I am using since I didn't think I would reach 8.2. I am hitting 8.2 only a few times a night, so I may raise my nominal to 8.3 and see how the system behaves.
     
  16. Mortie31

    Mortie31 Well-Known Member

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    Hi Bob I've sorted it... it was so simple, in ph control I alarm to active with a deviation of 0.5 ph and deactivate control set to yes, I set the nominal ph to 8.0 them I disabled controller. My doser is in plug 2 so I set that to ph value 1 - Alarm and inverted. I have tested this with high ph calibration fluid and it works a charm, turns back on as well as soon as ph probe is back in normal ph tank water... I would be happier with a smaller deviation say 0.3 but a ph of 8.5 would not devastate my tank. Strangely to me an alarm trigger turns the allied socket on so you have to invert it, to get it to turn off, I guess we'll get there with this programming eventually lol.
    Thanks for your help..
     
  17. Bob Stohrer

    Bob Stohrer Well-Known Member

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    Hi Mortie,

    Great! I'm going to look into what you did. I'm essentially after the same result but with added layers of complexity and PL. I am using kakwasser as my sole ATO water. My biggest worry is that it will dump 20 gallons of kalk at once, so I need a foolproof shutoff point or two.

    No problem with the help! It forced us both to think and learn.

    Bob
     
  18. reef fish

    reef fish Well-Known Member

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    hello everyone i may be late am trying set the same but not to run an dosing pump i have geo reef reactor don't know how to set it up with the ph
    i want to run the pump 2-3 a day for 10 sec in the time the ato can not pass water though
    the if ph is high shut off am a bit lost some plz help ......
     
  19. Bob Stohrer

    Bob Stohrer Well-Known Member

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    I'm having trouble understanding your system and what you want to do. Please explain more clearly. I or someone else should be able to help.
     
  20. reef fish

    reef fish Well-Known Member

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    SORRY WHAT THE BEST WAY TO SETUP A KALK REACTOR
     
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