Apex Salinity Probe

[ReefDreamz]

My salinity probe is reading 42 ppm when the actual salinity is 35 ppm. What am I doing wrong? I've calibrated it a dozen times. I've tried the Neptune calibration solution, the Hanna calibration solution and most recently just calibrated in my tank which I know is 35 ppm (Hanna Marine Monitor, ICP, Tropic Marin Hydrometer (temp adjusted) all read 35 ppm), but no matter what the Apex displays 42 for 35. I have my TC factor set to 2.1, I'm also using the SPS kit, I'm calibrating using a probe storage cap upside down as so many instruct. The reading is steady at 42 so it's not a huge deal, I know 42 is actually 35 but why the heck is this thing so dumb?

 

[Reeferbadness]

I have two tanks, each with its own Apex, and had a similar problem with both salinity probes. Mine weren't as far off as yours - both are around 37ppm when i know 100% that it should be 35ppm, even after multiple times calibrating. I eventually gave up and just watch them for larger movements above or below the false reading of 37 vs trying to get it exact.

 

[PigDaddyF15E]

One thing...may/may not be an issue: They are sensitive to electrical current. check that the probe cable isn't running right next to a power cable for something else. Might help....

 

[ReefDreamz]

I have two tanks, each with its own Apex, and had a similar problem with both salinity probes. Mine weren't as far off as yours - both are around 37ppm when i know 100% that it should be 35ppm, even after multiple times calibrating. I eventually gave up and just watch them for larger movements above or below the false reading of 37 vs trying to get it exact.

Yeah short of buying another probe for 200 bucks and hoping it will show 35 ppt I'm just going to do the same thing.

 

[ReefDreamz]

One thing...may/may not be an issue: They are sensitive to electrical current. check that the probe cable isn't running right next to a power cable for something else. Might help....

It's not directly touching any power cables but it is within 3 inches of a powerhead power cable.

 

[PigDaddyF15E]

It's not directly touching any power cables but it is within 3 inches of a powerhead power cable.

If you can...might try and get it as far from any other electrical cable as possible and try the calibration. I don't know your setp...but mine ran into a cabinet...well...all those cables come into the cabinet in the same spot. Not saying it's the reason...but if you have the ability to isolate it as much as possible.

Another thing...I thought I saw something somewhere about unplugging it...powering off the apex...powering on...then plugging in the salinity probe before you calibrate.

Not saying they don't act up though...mine is currently reading 30.0 after several calibration with three different fluids...and I have no idea why. Multiple other "manual" (refractometer and bulb hydrometer) both confirm 35.0

I really wish they had a way to just force it "whatever value you think it is right now...it's 35.0"...

 

[All_talk]

Have you tuned you TC factor, mine is currently 1.9 and seem pretty close. This is a good read...

(Almost) Everything You Need to Know About Apex Salinity Calibration and TC Factor

I was trying to calibrate my new salinity probe a few weeks ago, and ran into all sorts of problems. Calibrations that were way off the mark, big fluctuations in readings that couldn't possibly be correct (and were verifiably not), etc. After...

www.reef2reef.com

Calibrating to the tank water (in the tank) made a difference for me, it corrected the offset and reduced the fluctuation. The image below shows before and after the in-tank calibration.

 

[ReefDreamz]

Yes! I am using 2.1 TC factor but I haven't tried changing it. My last calibration I did to the tank water, it's very steady now but didn't fix the 42=35 thing.