Do I need to calibrate Milwaukee ORP probe for Apex?

JCOLE · Jan 7, 2020

I picked up another PM1 module yesterday to monitor the temperature in my Frag Tank. I don't have an ORP probe so I figured now would be a good chance to add one. I picked up a double junction Milwaukee probe from Amazon. I also ordered some 400mv ORP calibration solution. I went to calibrate the probe last night through the apex display and it was first asking for the Quin-7 calibration solution. I do not have that solution so I decided not to calibrate. I went ahead and just put it into my Frag Tank. It first read around 197 and now it is up to around 247 this morning.

Do you think I need to calibrate the probe or just keep these numbers as a baseline?

Screenshot_20200107-114547_Apex Fusion.jpg

JCOLE · Jan 8, 2020

n2585722 · Jan 8, 2020

The Apex has to be calibrated if the probe is changed regardless of the brand. It is good to wait a couple of days before calibrating a new probe. This will give it time to acclimate. I am not sure of the calibration process for the Apex though.

JCOLE · Jan 8, 2020

n2585722 said:
The Apex has to be calibrated if the probe is changed regardless of the brand. It is good to wait a couple of days before calibrating a new probe. This will give it time to acclimate. I am not sure of the calibration process for the Apex though.

Do you know where I can get the Quin-7 calibration solution?

n2585722 · Jan 8, 2020

h2oh2o said:
Do you know where I can get the Quin-7 calibration solution?

The controller I have uses the 400 solution. This is the first time I heard of Quin-7 solution.

ca1ore · Jan 8, 2020

Frankly I see no compelling reason to caibrate an ORP probe. A new probe can take a couple of weeks to settle anyhow. Not like you’re going to trigger any actions based on specific readings.

JCOLE · Jan 9, 2020

ca1ore said:
Frankly I see no compelling reason to caibrate an ORP probe. A new probe can take a couple of weeks to settle anyhow. Not like you’re going to trigger any actions based on specific readings.

That's true. I am just going to have it for monitoring only. Would like it to be accurate though.

JCOLE · Jan 9, 2020

n2585722 said:
The controller I have uses the 400 solution. This is the first time I heard of Quin-7 solution.

When you calibrate the ORP probe from apex display module it ask you for the Quin-7 solution first then you can go to the 400mv solution. I read this on the Neptune forum from Zombie "You need quinhydrone and pH 4.0 and pH 7.0 to calibrate the orp probe on the apex." He also states that it doesn't need to be calibrated unless using ozone. He also suggested to test the probe in the 400mv solution to see how accurate the probe is.

Makes since. I will go this route first. Thanks everyone

ca1ore · Jan 9, 2020

h2oh2o said:
That's true. I am just going to have it for monitoring only. Would like it to be accurate though.

Understood! I've generally viewed ORP as mostly useless though. Let's say your probe reports 350 when the tank is actually at 370. What would you do differently? In my case, the answer is nothing. In fact, in the 20 years since I last used ozone, I have not intervened even a single time based on an ORP reading .... not once LOL. Just sayin.