Weird Salinity Change

[Tidepowder]

My tank evaporated about a gallon and a half. I have my tank's salinity usually around 30-32 ppt, but when I checked it was at 25-26 ppt. I still topped-off with freshwater anyway. Then I checked the salinity again. Surprisingly, it raised to 29 ppt.

Has there ever been a case like mine here.

 

[Jay Hemdal Verified Community Expert]

My tank evaporated about a gallon and a half. I have my tank's salinity usually around 30-32 ppt, but when I checked it was at 25-26 ppt. I still topped-off with freshwater anyway. Then I checked the salinity again. Surprisingly, it raised to 29 ppt.

Has there ever been a case like mine here.

Salt can't leave the water and then return like that. Measurement errors can cause can cause issues like this. What method are you using to measure salinity?
What size tank is it?


jay

 

[exnisstech]

No way salinity can go down as water evaporates then increase when fresh water is added.

 

[BanZI29]

Agreed with above. What did you use to check your salinity?
the ONLY way that could happen is if there was salt build up somewhere either on the edge of your tank or sump (which MIGHT cause the drop), from evaporation and when you added, the water level raised and dissolved the salt back in. Other than that, I would say it was an equipment oops.

 

[Tidepowder]

Agreed with above. What did you use to check your salinity?
the ONLY way that could happen is if there was salt build up somewhere either on the edge of your tank or sump (which MIGHT cause the drop), from evaporation and when you added, the water level raised and dissolved the salt back in. Other than that, I would say it was an equipment oops.

I'm using a refractometer. I'm guessing maybe it was my refrac, there was probably a temperature difference or a calibration error.

 

[Garf]

I'm using a refractometer. I'm guessing maybe it was my refrac, there was probably a temperature difference or a calibration error.

I’d be calibrating with a DIY solution, courtesy of Mr Randy Holmes Farley;

http://www.reefkeeping.com/issues/2004-06/rhf/index.php

 

[Jay Hemdal Verified Community Expert]

I'm using a refractometer. I'm guessing maybe it was my refrac, there was probably a temperature difference or a calibration error.

If your refrac has automatic temperature compensation, that would reduce the issue. If it was mis calibrated, you would get consistent, but incorrect readings, not variable readings. I see most variable readings with swing arm hydrometers that get a bubble attached to the arm, changing the reading. With a refrac, leaving some freshwater on the plate between readings could cause this, not sure what the other cause would be.

Jay

 

[Garf]

Unintentional swapping between PPT and S.G. perhaps. Or fiddly finger syndrome. Either way, it needs calibrating.