Sudden Drop in Salinity

Dubs83 · Aug 15, 2017

Hello! So over the last few days I've noticed a pretty large drop in salinity. I've had no problem keeping the SG right at 35ppt (according to the apex) until I had a problem with my Break Out Box which controls my ATO. It unplugged and because it was configured to show OPEN when in need of a top off (my fault). That's been fixed and now stops all top off water when it shows OPEN. However, my salinity has been dropping pretty steadily from 33 to 30.7 as of this morning. There are no leaks... the only change is I've put a dehumidifier in the basement where my fish room/Sump is. I'm away from home and haven't had a chance to check my salinity via a refractometer but other than a salinity probe that needs calibration, is there anything else that could be causing the salinity to drop?

Randy Holmes-Farley · Aug 15, 2017

The only way salinity can drop much is to add fresh water. To drop from 33 to 30.7 ppt means that the total water volume would need to increase by 7.5%, or 7.5 gallons in a 100 gallon system.

If that didn't happen, then it must be testing error somehow.

Dubs83 · Aug 15, 2017

Randy Holmes-Farley said:
The only way salinity can drop much is to add fresh water. To drop from 33 to 30.7 ppt means that the total water volume would need to increase by 7.5%, or 7.5 gallons in a 100 gallon system.

If that didn't happen, then it must be testing error somehow.

Okay. That's what I'm thinking is happening. Thank you, Randy, for putting my mind at ease