Apex PM2 w/conductivity probe stable reading?

Philly Reefer · Sep 28, 2020

I am having a hard time trusting my conductivity probe.
Its staying on 32.4 all the time.
I moved my temp probe from the head to the PM2. And thats working ok.

So.. is this normal? Do I have the most stable salinity in my tank?

Calibration was ran and it showed 34.8 in the solution. Apex support said its working correctly.

I do have a slight suspicion on my refractometer. It is showing 35ppt but somehow my dKh always lower than 7dkh in a newly mix tropic marin pro reef saltwater.(6.5dkh).
Refractometer calibration using brightwell. Another calibration solution is coming.

PS: that peak is because I mixed some new saltwater in a bowl to test this out

Wiskey · Sep 28, 2020

I'd have a hard time trusting it, just because I've never had a stable reading from that thing. This is about the best it's ever been. This tank has an auto topoff and the salinity really doesn't change:

Philly Reefer · Sep 28, 2020

Wiskey said:
I'd have a hard time trusting it, just because I've never had a stable reading from that thing. This is about the best it's ever been. This tank has an auto topoff and the salinity really doesn't change:

Hey Wiskey,
Thank you for the response.
At least yours are moving up and down. Mine stays 32.4 almost around the clock. I also have ATO but I have a hard time believing that its that stable though.

Wiskey · Sep 28, 2020

aior0s said:
Hey Wiskey,
Thank you for the response.
At least yours are moving up and down. Mine stays 32.4 almost around the clock. I also have ATO but I have a hard time believing that its that stable though.

That's what I mean,.. those things are not known to be particularly reliable. Stray voltage effects them allot, so does a stray air bubble. I would guess that something is wrong if it's rock solid.

Have you tried putting it in water that's diluted to see if it tracks changes?

Whiskey

Philly Reefer · Sep 28, 2020

Wiskey said:
That's what I mean,.. those things are not known to be particularly reliable. Stray voltage effects them allot, so does a stray air bubble. I would guess that something is wrong if it's rock solid.

Have you tried putting it in water that's diluted to see if it tracks changes?

Whiskey

Yes. I pulled it out and its 0. Put it on the new water I mixed in the bowl. Thats how I got the peak.

So it is seems to be working... But as you mention, with the track record of this probe, I am very skeptical.

LoL

I am waiting for another solution in the mail cause my LFS ran out of them

radiata · Sep 30, 2020

I've been pretty happy with my Apex salinity probe since I got it away from some electrical interference.

I keep my test water measurements on a spreadsheet.

Here's an example:
My Apex salinity probe shows 32.2
My Milwaukee Specific Gravity measures 1.025
When I run the probe's 3.2 reading through the algorithm to convert it to SG, I get 1.02546
Which is sure close enough for me!
To do the conversion you multiply the probe 's reading by 0.0008 and then add 0.9997.

I'd like to credit the party who supplied the conversion algorithm, but I have no idea where I found it.
Feel free to claim the credit if you're the one...

Philly Reefer · Sep 30, 2020

radiata said:
I've been pretty happy with my Apex salinity probe since I got it away from some electrical interference.

I keep my test water measurements on a spreadsheet.

Here's an example:
My Apex salinity probe shows 32.2
My Milwaukee Specific Gravity measures 1.025
When I run the probe's 3.2 reading through the algorithm to convert it to SG, I get 1.02546
Which is sure close enough for me!
To do the conversion you multiply the probe 's reading by 0.0008 and then add 0.9997.

I'd like to credit the party who supplied the conversion algorithm, but I have no idea where I found it.
Feel free to claim the credit if you're the one...