Programming Help, Unique scenario

[RRand]

I am not sure if I have this in the right place. If not, I apologize in advance.

I just purchased my first Apex system and am trying to learn the programming end. I do not use this system to control a fish tank. I am a manufacturer and I am using this system in our R&D facility to monitor pH and temp, turn on and off pumps, and to add certain chemicals to our treatment system using DOS. I have the system programmed based on what I have read in this forum however I am hoping to change the way it functions.

Right now I have the DOS #1 set to the following:
Set OFF
If pH > 4.40 Then ON
If pH < 4.30 Then OFF

There are problems with the above though. Our system has 750 gallons of water. Our circulation pump turns all this volume every 15 minutes. By the time the pH changes to 4.30 and shuts the DOS off, there is too much acid added to the system. Over the next 5 minutes, the pH falls to 3.5. The DOS is typically adding around 200mL of acid at a time, which is too much. I have moved the DOS input as close to the probe as possible.

What I would like, if possible:
When pH hits 4.40 the DOS turn on and pumps 25ml of acid. Then the system waits for 15 minutes before cycling again. If after 15 minutes the pH is still above 4.40, the DOS pumps another 25ml of acid.

There is no risk of 25ml of acid ever being too much to add. Is this possible? if so, can someone detail walk me through how to achieve this?

[zombie]

Create a DOS profile that will dispense 25ml at the slowest rate, set the interval to 900 seconds and set the count to whatever you are comfortable with adding before you think it might become a problem (like maybe the pH probe failed or something) replace ON in your code with the profile name.

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[RRand]

Create a DOS profile that will dispense 25ml at the slowest rate, set the interval to 900 seconds and set the count to whatever you are comfortable with adding before you think it might become a problem (like maybe the pH probe failed or something) replace ON in your code with the profile name.

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Thank you. I am looking at the profile page and see PF 1 - 32. I assume I can change any one of them as they are not in use.

If I use PF1
Name: DOS_Control
Type: DOS
Dose Rate: 60mL/Min
Direction: Forward
Per DOse Amount: 25ml
Dose intervals: 900
Dose Count: 1 (I do not understand what you mean when you say what you are comfortable adding. Are you saying after it does 1 count it will no longer dose until ???)

DOS Config
Set OFF
If pH > 4.40 Then DOS_Control

[zombie]

I would adjust to something like this

If I use PF1
Name: DOS_Control
Type: DOS
Dose Rate: 14mL/Min
Direction: Forward
Per DOse Amount: 25ml
Dose intervals: 900
Dose Count: 10

DOS Config
If pH > 4.40 Then DOS_Control
If pH < 4.35 Then OFF


This will run hysteresis and will very slowly add the acid over 2 minutes, which would likely help the stability. If pH is still above 4.35, the profile will try again 13 minutes later. The dose count acts as a maximum number of retrys before it stops trying. You could be alerted when this happens using the following format (example is for 10 retrys). You could then investigate the issue and reset it by setting the DOS to OFF and then back to AUTO.

DOSfail
Set OFF
If Output DOSname = ON Then ON
Defer 150:00 Then ON

Email
(Existing)
If Output DOSfail = ON Then ON


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[RRand]

I would adjust to something like this

If I use PF1
Name: DOS_Control
Type: DOS
Dose Rate: 14mL/Min
Direction: Forward
Per DOse Amount: 25ml
Dose intervals: 900
Dose Count: 10

DOS Config
If pH > 4.40 Then DOS_Control
If pH < 4.35 Then OFF


This will run hysteresis and will very slowly add the acid over 2 minutes, which would likely help the stability. If pH is still above 4.35, the profile will try again 13 minutes later. The dose count acts as a maximum number of retrys before it stops trying. You could be alerted when this happens using the following format (example is for 10 retrys). You could then investigate the issue and reset it by setting the DOS to OFF and then back to AUTO.

DOSfail
Set OFF
If Output DOSname = ON Then ON
Defer 150:00 Then ON

Email
(Existing)
If Output DOSfail = ON Then ON


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Thank you. This is working well. Last question. The DOSFAIL command you linked, does that go into the programming under "If pH < 4.35 Then OFF"?

[zombie]

Thank you. This is working well. Last question. The DOSFAIL command you linked, does that go into the programming under "If pH < 4.35 Then OFF"?

No. DOSfail would be a virtual outlet and you throw that last line in your email alarm to get alerted.

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