Salinity goes up when temperature goes down

[Bramzor]

Today I noticed that the cable was not where it was supposed to be and that the fluctuations where related to enabling/disabling of the light above the sump.

So I rerouted the cable. On first sight it's a lot more stable now but we'll have to see for a few days if this was the fix. When plugging out and in the cable I noticed that it was not a normal (shielded) probe cable like for example PH. Probes with shielded cables are less prone and the PH was routed in the same way and was not impacted by the issue.

Anyway, I might get it stable after all.

 

[Randy Holmes-Farley Verified Community Expert]

I am not really sure what about the temp makes it move. Mine moves even when I turn then temp compensation off even. I truly think the temp compensation does little to nothing to the salinity readings. Ph on the other hand is very temp compensated,.

You may understand all of what I’m about to say, so don’t be offended if you do.

While the temp correction needed for a 0.1 deg temp change is small, the correction becomes far larger for larger temp changes.

With no correction at all, apparent salinity will rise as temp rises just because conductivity that is not temp corrected rises with temperature. Correction is supposed to normalize conductivity to 25 deg C.

 

[Bramzor]

I recalibrated the probe and was showing 35 stable on the calibration fluid. After putting it back in the tank, it showed a stable 34 which was expected (this is what I use for my waterchanges). But a few days later, it's going up again and keeps going up.

Made sure the cable was guided on the side and not crossing any other cables. Did dose a few drips of high concentrated Calcium but this shouldn't increase salinity 2 days later. Also dosed KZ Cyano Clean but same logic here... Also water level is fine and ATO working correctly.
Tested with a refractometer and it also showed 35 so it might as well be true... But how did it go up this fast in just 24h.

I did dose some Tropic Marin CarboCalcium days ago. Is it possible that calcium formate increases salinity after a long time? Checked KH which was 6.8 so I guess it's not related as this value would go up too if it's the calcium formate right?

 

[Randy Holmes-Farley Verified Community Expert]

I recalibrated the probe and was showing 35 stable on the calibration fluid. After putting it back in the tank, it showed a stable 34 which was expected (this is what I use for my waterchanges). But a few days later, it's going up again and keeps going up.

Made sure the cable was guided on the side and not crossing any other cables. Did dose a few drips of high concentrated Calcium but this shouldn't increase salinity 2 days later. Also dosed KZ Cyano Clean but same logic here... Also water level is fine and ATO working correctly.
Tested with a refractometer and it also showed 35 so it might as well be true... But how did it go up this fast in just 24h.

I did dose some Tropic Marin CarboCalcium days ago. Is it possible that calcium formate increases salinity after a long time? Checked KH which was 6.8 so I guess it's not related as this value would go up too if it's the calcium formate right?

A calcium addition for a couple of days wouldn’t make much salinity difference. Calcium formate alone won’t increase salinity at all over time if calcium is held steady, but they may add some other ingredients that could have a very small salinity boost.