Calibrating a Apex COND probe fails

[Jyetman]

So my PM2 module was repaired and when I plugged it back in my COND was reading higher. I know it was off today when I pulled the probe out of the water and it was reading 3.5 instead of zero. So I decided to go ahead and calibrate it with pinpoint 5300 solution. The bottle was from last November and half empty wrapped tight in a baggy stored in a sealed container. Short story it doesn't calibrate to specs. Tested the solution with a Milwaukee ma887 says 37 PPT should be 35 PPT. After many attempts I said a few curse words and made my own solution since I know what my tank parameters are suppose to be. During the calibration phase I added drops of fresh RO water to the solution until the apex read 35 PPT. The tank water now reads where I want it 34 PPT. Does the calibration fluid go bad even if stored in sealed bottles? If I remember correctly last year when I calibrated it was extremely difficult must have fudged it then too.

[slief]

Probe calibration solution doesn’t store well once opened. It’s best to use the stuff in the sealed foil bags for calibrating. My guess is that there has been some evaporation from the bottle itself and the solution is no longer inaccurate as indicated by your Milwaukee.

[Jyetman]

Originally Posted by slief

Probe calibration solution doesn’t store well once opened. It’s best to use the stuff in the sealed foil bags for calibrating. My guess is that there has been some evaporation from the bottle itself and the solution is no longer inaccurate as indicated by your Milwaukee.

Where do you buy the packets? I looked on amazon, Foster & Smith and Aquacave just the bottles are available.

[slief]

Originally Posted by Jyetman

Where do you buy the packets? I looked on amazon, Foster & Smith and Aquacave just the bottles are available.

Here is a 5 pack for a good price. Just select the 53 ms from the pull down.
https://www.marinedepot.com/Neptune_...FITECL-vi.html

A single pack on Amazon for a high price.
https://www.amazon.com/Neptune-Syste...dp/B01BPFX1KY/


Bulk Reef Supply with a very good price on single packets.
https://www.bulkreefsupply.com/neptu...n-53-0-ms.html

Aquacave..
http://www.aquacave.com/neptune-syst...n-53-0-ms.html

[Jyetman]

Originally Posted by slief

Here is a 5 pack for a good price. Just select the 53 ms from the pull down.
https://www.marinedepot.com/Neptune_...FITECL-vi.html

A single pack on Amazon for a high price.
https://www.amazon.com/Neptune-Syste...dp/B01BPFX1KY/


Bulk Reef Supply with a very good price on single packets.
https://www.bulkreefsupply.com/neptu...n-53-0-ms.html

Aquacave..
http://www.aquacave.com/neptune-syst...n-53-0-ms.html

Thank You plan on adding a few to my black Friday list. For the meantime can I adjust the Temp Compensation to match the proper reading for my tank?

[slief]

Originally Posted by Jyetman

Thank You plan on adding a few to my black Friday list. For the meantime can I adjust the Temp Compensation to match the proper reading for my tank?

Probably.. I have never tried that myself.