Conductivity meters and ground probes

[Cory]

About 10 years ago I had a pinpoint condictivty meter to measure saltiness. Problem was long story short, using the wall power supply gave faulty readings but with a battery it was identical to my refractometer.

Anyways, i was thinking would a ground probe ground the electrodes of one and mess with the readings?

 

[chipmunkofdoom2]

I can't answer this for sure. I can say that I get different readings from my conductivity meter when the pumps are on vs off. I typically take a small sample of saltwater in a cup and use my conductivity meter to measure that, just so the electrical interference generated by the pumps does not affect my readings.

@Brew12 may be able to offer some insight.

 

[Brew12]

I can't answer this for sure. I can say that I get different readings from my conductivity meter when the pumps are on vs off. I typically take a small sample of saltwater in a cup and use my conductivity meter to measure that, just so the electrical interference generated by the pumps does not affect my readings.

@Brew12 may be able to offer some insight.

Thanks for the invite!

About 10 years ago I had a pinpoint condictivty meter to measure saltiness. Problem was long story short, using the wall power supply gave faulty readings but with a battery it was identical to my refractometer.

Anyways, i was thinking would a ground probe ground the electrodes of one and mess with the readings?

The ground probe should help reduce the impact from induced electricity in the system.

What you were seeing with the wall power supply was likely due to noise from the 120VAC making it through to the low voltage DC sensing circuit. By using a battery, you provided the low voltage DC directly, so no noise. A ground probe helps drive the AC voltage in the water closer to zero which, while not as effective as having no AC sources around, should reduce its impact.

 

[Cory]

Thanks for the invite!


The ground probe should help reduce the impact from induced electricity in the system.

What you were seeing with the wall power supply was likely due to noise from the 120VAC making it through to the low voltage DC sensing circuit. By using a battery, you provided the low voltage DC directly, so no noise. A ground probe helps drive the AC voltage in the water closer to zero which, while not as effective as having no AC sources around, should reduce its impact.

So a ground probe should be beneficial when using conductivuty in the tank?

Id love to try this test in a cup of tabk water and a ground probe in it and out. Dont have one anymore

 

[Brew12]

So a ground probe should be beneficial when using conductivuty in the tank?

Id love to try this test in a cup of tabk water and a ground probe in it and out. Dont have one anymore

Yup, it should be helpful. The only way it should cause a problem is if the ground probe was right up against the edge of the conductivity probe.

 

[Randy Holmes-Farley Verified Community Expert]

I think the issue with some of the Pinpoints on 110v was electrical interference pickup in the electric cord and such, not that there's any connection of the probe to the mains that impacts the effect of a ground probe.

 

[Cory]

I think the issue with some of the Pinpoints on 110v was electrical interference pickup in the electric cord and such, not that there's any connection of the probe to the mains that impacts the effect of a ground probe.

I wonder if we grounded the electric cord, would it stop that issue?

 

[Randy Holmes-Farley Verified Community Expert]

I wonder if we grounded the electric cord, would it stop that issue?

How would you ground an insultated two wire electric cord? Shielding it with metal might help, like inside a pipe.

 

[Cory]

How would you ground an insultated two wire electric cord? Shielding it with metal might help, like inside a pipe.

Ah yes. I was thinking of like a metal sock mesh over the cord then plug it into the ground.

 

[Brew12]

I can't say inductance from the cord isn't an issue, but I find it unlikely. I think it is more likely that the inaccuracy was caused by ripple in the rectifier of the unit.

Oh, and the cord is already grounded. The neutral conductor is tied to your homes ground inside the panel if it is installed correctly.

 

[Randy Holmes-Farley Verified Community Expert]

I can't say inductance from the cord isn't an issue, but I find it unlikely. I think it is more likely that the inaccuracy was caused by ripple in the rectifier of the unit.

Oh, and the cord is already grounded. The neutral conductor is tied to your homes ground inside the panel if it is installed correctly.

Well ripple my rectifier! lol

Can't say where exactly it is happening, but this is the sort of report that folks sometimes give:

http://www.reefcentral.com/forums/showpost.php?p=11961531&postcount=25

"It turned out that it was just interference from the light hood. My new complaint about my Pinpoint monitor is that new 9v batteries only last a week. Ah, I guess I'm hard to please but I'll be buying some rechargeable 9vs this weekend. "

 

[Brew12]

Well ripple my rectifier! lol

Can't saw where exactly it is happening, but this is the sort of report that folks sometimes give:

http://www.reefcentral.com/forums/showpost.php?p=11961531&postcount=25

"It turned out that it was just interference from the light hood. My new complaint about my Pinpoint monitor is that new 9v batteries only last a week. Ah, I guess I'm hard to please but I'll be buying some rechargeable 9vs this weekend. "

Other equipment cords can cause problems although I would guess in this case he used T5 lights or metal halides. Those can really mess with sensitive electrical test equipment.