I have 0.5 stray voltage. Is that enough to throw off my conductivity probe?

RussC · 07/21/2018, 05:07 PM

I'm banging my head against the wall trying to chase down why my Apex 2016 salinity probe has recently decided to fluctuate. I know its not accurate. So I checked for stray voltage. I have 0.5 volts and I can't find the culprit. The heater was suspect #1. it did reduce voltage by 0.2. But still, is this 0.5 really an issue? I'm done with the bubbles being the suspect. I've had this thing recalibrated three times, placed in three different locations in my sump and carefully done every trick in the book to either eliminate or prevent bubbles. Its not bubbles. Not all these times.

So I tried something. I put the tank water in a cup and put the probe in the cup. Its actually reading closer to accurate. It was about 3 points off in the tank. Uhhhh! This has been a frustrating ghost chase.

Here's one more wrench in the works. As I sit here the readings are dropping. Same thing that happens after every time I recalibrate. Things start off right on the mark and then slowly stat to fall. No bubbles in the cup. The only variable I no longer control in the cup is temperature. But even it hasn't change.

Is this probe failing or do I have something else I need to look at?

mcgyvr · 07/21/2018, 05:18 PM

The voltage is totally normal/fine..
You can walk around your house with the probes in the air and pick that up all over the place..

Have you tried moving the probe to different places in the tank..
Its certainly possible that localized interference can cause issues..

RussC · 07/21/2018, 05:36 PM

I have tried three locations in that sump for the probe. Each location a different "chamber" of the sump. I've tried different depths for the probe too. At first I thought it was bubbles. But I've gotten away from that because of all the different things I've tried and each attempt giving me the basically the same result.

I also felt like .5 volts was really nothing to be concerned about. But at this point, trying to figure out what's up with my probe has me really brainstorming. I may end up just buying a new probe and installing it to see what happens.

Joe0813 · 07/21/2018, 06:07 PM

ive had issues with my apex salinity probe.. I have realized that these are VERY sensitive to micro bubbles in the sump. If I don't shake the bubbles out once a week the readings go nuts

RussC · 07/21/2018, 07:22 PM

would there be any reason you couldn't invert the probe? At least then the bubbles couldn't collect inside the probe. The probe would be completely submerged, though. Is that doable?

07/21/2018, 05:18 PM	#2
mcgyvr Registered Member Join Date: Sep 2003 Location: North Carolina Posts: 20,050	The voltage is totally normal/fine.. You can walk around your house with the probes in the air and pick that up all over the place.. Have you tried moving the probe to different places in the tank.. Its certainly possible that localized interference can cause issues.. __________________ Who me?

07/21/2018, 05:36 PM	#3
RussC Registered Member Join Date: Jan 2003 Location: Gulfport (Mississippi Gulf Coast) Posts: 1,405	I have tried three locations in that sump for the probe. Each location a different "chamber" of the sump. I've tried different depths for the probe too. At first I thought it was bubbles. But I've gotten away from that because of all the different things I've tried and each attempt giving me the basically the same result. I also felt like .5 volts was really nothing to be concerned about. But at this point, trying to figure out what's up with my probe has me really brainstorming. I may end up just buying a new probe and installing it to see what happens. __________________ When a habit begins to cost money, it's called a hobby! Current Tank Info: Red Sea Reefer XL 425 Alive and Kick'n BOD 8-29-17

07/21/2018, 06:07 PM	#4
Joe0813 Registered Member Join Date: Mar 2011 Location: Boston strong Posts: 2,766	ive had issues with my apex salinity probe.. I have realized that these are VERY sensitive to micro bubbles in the sump. If I don't shake the bubbles out once a week the readings go nuts __________________ Joe and Jenny Current Tank Info: 180 reef

07/21/2018, 07:22 PM	#5
RussC Registered Member Join Date: Jan 2003 Location: Gulfport (Mississippi Gulf Coast) Posts: 1,405	would there be any reason you couldn't invert the probe? At least then the bubbles couldn't collect inside the probe. The probe would be completely submerged, though. Is that doable? __________________ When a habit begins to cost money, it's called a hobby! Current Tank Info: Red Sea Reefer XL 425 Alive and Kick'n BOD 8-29-17

07/21/2018, 05:07 PM	#1
RussC Registered Member Join Date: Jan 2003 Location: Gulfport (Mississippi Gulf Coast) Posts: 1,405	I have 0.5 stray voltage. Is that enough to throw off my conductivity probe? I'm banging my head against the wall trying to chase down why my Apex 2016 salinity probe has recently decided to fluctuate. I know its not accurate. So I checked for stray voltage. I have 0.5 volts and I can't find the culprit. The heater was suspect #1. it did reduce voltage by 0.2. But still, is this 0.5 really an issue? I'm done with the bubbles being the suspect. I've had this thing recalibrated three times, placed in three different locations in my sump and carefully done every trick in the book to either eliminate or prevent bubbles. Its not bubbles. Not all these times. So I tried something. I put the tank water in a cup and put the probe in the cup. Its actually reading closer to accurate. It was about 3 points off in the tank. Uhhhh! This has been a frustrating ghost chase. Here's one more wrench in the works. As I sit here the readings are dropping. Same thing that happens after every time I recalibrate. Things start off right on the mark and then slowly stat to fall. No bubbles in the cup. The only variable I no longer control in the cup is temperature. But even it hasn't change. Is this probe failing or do I have something else I need to look at? __________________ When a habit begins to cost money, it's called a hobby! Current Tank Info: Red Sea Reefer XL 425 Alive and Kick'n BOD 8-29-17