Neptune Apex Salinity Probe Calibration

[TinyChocobo]

Hello!

I set my Apex up just the other day but I'm having some issues getting the salt probe to calibrate.

I did put it in my sump water in a probe holder for a couple of days to let it 'hydrate' and then took it out and rinsed it in RO/DI and let it dry before trying the calibration process.

It does the 'settling' and then 'within range' for the dry/first step but when it goes to the second step in the calibration solution it will settle - and the time will run out without it ever going 'in range'.

I tried a manual calibration and the first number was ~66 and the second number was ~230. I was able to calibrate it using the manual method but then it reads the tank as ~5 PPT when it's 35 PPT according to my Milwaukee Refractometer.

If I put it in the calibration solution it does show ~35 PPT - which is odd - because it says on the packet that it should not read 35 PPT to a refractometer - perhaps it will only read that way for a salinity probe that checks conductivity?

Either way - it seems to me that the calibration fluid is correct [as it reads 35 PPM in the Apex when in the calibration solution] and it seems that the probe itself is fine as well - otherwise it wouldn't read 35 PPM in the solution... So what am I missing?

I did float the calibration solution in my sump for a while to bring it up to temp.

 

[DLHDesign]

Some common problems for this include;
- Electrical noise. Ensure that the probe cord isn't wrapped around any other cables (power cords especially) - or even traveling next to them for any significant length.
- Bubbles trapped in the probe. Gently shake the probe while it's in the solution while the holes in the probe are upright (higher than anything else)
- Keep the calibration solution in the tank water during calibration (temperature matters all the way through)

Here's a video from BRS that may help, in case you've not seen it yet.

 

[HolisticBear]

Some common problems for this include;
- Electrical noise. Ensure that the probe cord isn't wrapped around any other cables (power cords especially) - or even traveling next to them for any significant length.
- Bubbles trapped in the probe. Gently shake the probe while it's in the solution while the holes in the probe are upright (higher than anything else)
- Keep the calibration solution in the tank water during calibration (temperature matters all the way through)

Here's a video from BRS that may help, in case you've not seen it yet.

Great tips

 

[TinyChocobo]

I did all of that but I have some new solution on its way from BRS and will try again.

I have this cable running all by itself from the apex to the solution - I was careful about it’s routing.

 

[rocsec1]

I find mine to be of a guide then a dependable emasurement. I check the water with my Hanna and then make note of what the apex is reading. If it varies from this number I check the water to see if there is a problem.

 

[TinyChocobo]

So I removed the salinity sensor from the salt water, rinsed it in ro, and put it back in and suddenly it’s reading 31.6 and climbing ... it was only reading 5-7 before.

Maybe it’s ready to calibrate now.