pH probe interference

[John Neuzil]

I have my pH probe connected to my control 4. It will be reading 8.0 but as soon as my Icecap Algae Scrubber comes on the pH rises to 8.3. My first thought was electrical interference from the power cord to the scrubber light being too close to the probe cord so I rerouted the probe so it was no where near any power cords. No change. The pH sill rises the moment the light to the scrubber comes on. What could be causing this?

 

[John Neuzil]

And just to clarify the change up and down is instant with the light going on and off. Even when I turn the pump off from the scrubber so the issue is not biological or gas exchange.

 

[MGarrison]

How close is the probe to the scrubber?
If you take the probe out and put it in a separate container the the same thing occur?

 

[MGarrison]

Also have you tried to measure if there is stray voltage when the scrubber is on?

 

[John Neuzil]

About two feet away and no stray voltage.