Chronic increment in pH & EC rates

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hey there,

I have been experiencing a chronic increment in pH & EC values after a while in my system. You can easily observe them through the charts below.

This represents the pH and the EC rates alone. You can see that it starts skyrocketing for no reason.

This represents the pH & EC function behavior w.r.t the pH values. I use 63% and 5% concentrated pH down (NO3) & up (KOH) solutions, respectively.

This represents the moments that A & B solutions were pumped into the water tank.

I have tried many things like changing the pH up & down brands and A & B nutritions and recalibrating the probes to solve the issue, but none of them worked. Lately, I have noticed that when EC gets involved in measuring the rates along with the pH probe, it starts affecting the pH measurement after a point and the values become unreliable concerning the actual rates. The weirdest thing is that no matter how much acid gets pumped into the water tank, it continues to climb. However, I measure between 0-1 (minus values to the end) as soon as I pull the EC probe off from the tank. Due to financial reasons and stock problems, I had to use DFRobot’s Gravity: Analog pH meter V2 and Seeed EC sensor including a single 16-bit ADC. Once, I came across the need for electrical isolation between the sensors over the Internet. I do not use any professional isolator or anything designed by me (no experience with this). But, I tried to separate the pH and the EC circuits by moving the pH circuit to an external ADC. I concluded that it is not counted as isolating the circuits since it didn’t work :slight_smile:

I would appreciate any suggestions and definitely want to hear about similar issues that are solved. Thanks in advance!

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I’ve only used Atlas Scientific pH and EC sensors, which include electrical isolation, so I haven’t had to work through this issue, but I’ve seen others have success using isolator circuits:

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I do have some problems reading pH on my setup!
I do not have any EC sensor, but I have a 12V Light Strip controlled with PWM. When I connect the light to the system, it creates erratic pH values. I have changed to a better pH sensor with internal reference, and got better readings. I will try some changes as soon as possible: put a capacitor to filter out the LED PWM output and see if this make any change. I will also try to use an B1205S DC-DC converter with isolation/decoupler. The aim is to isolate the ADS1115 together with the analog signal adapter for BNC sensors.
Here you can see how erratic it becames:

I am running mycodo to monitor a process that starts with pH near 7 and reaches near 8.6 in 4 days.

@KyleGabriel This analog isolator seems to work well. I like to mark your answer as the solution but it doesn’t appear. Is this feature no longer used?

Solutions are only for question categories and I believe only the Mycodo category is one.