Apex Salinity probe being stupid, help?

[Biff0rz]

Hey all, need some help with this sensor. I have an alarm state set if it drops below 30ppt. Starting last night the salinity drops suddenly. Mind you the sensor has been rock solid for 2+ mo. Sure it's off by 1ppt or so but it's been consistently off to where I'm confident of my salinity parameter vs my Hanna and refractometers. Last night and this morning I was near my tank when both alarms kicked off. I immediately fired up the Hanna and checked (its been calibrated this month) and salinity while the probe was reading 30-ish the Hanna read 34.7ppt. I checked the sensor in the sump, no air bubbles and it's sitting in low flow and on an angle with the Apex magnet holder.

Ideas of what to do? Calibrate the salinity probe again? Note, I have not made any changes to the system or touched the probe.

 

[Biff0rz]

Screen shot

 

[Biff0rz]

Bump

 

[Biff0rz]

no one has dealt with this, or maybe I should post under controllers?

 

[Daniel@R2R Verified Admin]

@SuncrestReef or @DarthSimon might be able to help

 

[SuncrestReef]

You’d be amazed at how many people insist there are no bubbles inside the probe. Try fully submerging the probe and then turn it upside down under water and tap it. Bubbles can then escape straight up out of the tube.

 

[Biff0rz]

You’d be amazed at how many people insist there are no bubbles inside the probe. Try fully submerging the probe and then turn it upside down under water and tap it. Bubbles can then escape straight up out of the tube.

Will try anything at this point, lol. I'll report back, thanks.

 

[vetteguy53081]

I have in the sump at an angle to allow the air bubbles to escape

 

[SuncrestReef]

I have in the sump at an angle to allow the air bubbles to escape

In my experience that’s not sufficient to prevent all bubbles from being trapped.

 

[DC Reefer]

If eliminating the bubbles doesn't work, I would recalibrate. Also how old is the probe? I have seen some info that they last 1-2 years and then need to be replaced. I have one probe that has been going for 3+ years (fingers crossed).

 

[Thaxxx]

In my experience that’s not sufficient to prevent all bubbles from being trapped.

Can you offer what is sufficient?

 

[AcanthurusRex]

Don't use an alarm with this probe. After my second probe failed I removed it.
I put it in the return section where there is fewer bubbles. Since I run the tank at 35ppt I calibrated in place. You must submerge it upside down an insure that there is no trapped air. I have had it work for long periods doing this method.
I would never consider this reliable enough for any control.

 

[SuncrestReef]

Can you offer what is sufficient?

I keep my salinity probe fully submerged upside down so no bubbles can get trapped inside the tube. Neptune says the cable will become brittle over time in salt water, but I’ve had mine under water for over two years now with no problems and stable readings.