Salinity issue

[hellasinc]

Hey guys,

Looking for some help cause im at my wits end, so im new to the hobby so any help would be greatly appreciated. The issue i have is my salinity keeps changing from 1.025 to 1.023 and I have no idea why. Example yesterday i mixed some red sea salt (blue bucket) for about an hour and then rose the temp to 25 degrees Celsius to get 1.025, changed the water and check the salinity and it was 1.025 . A couple of hours later I checked my tank again and still was 1.025 but when I check in the morning it was 1.023 and I don't know why and its not the first time its happened.

I have calibrated the refractometer with RO so I don't think that's the issue, but I have a feeling its the ATO as I have noticed the waterline increase over the last couple of days in my tank. Also noticed the water in the sump especially after putting more bioballs its higher for some reason. Can someone please help me ?

 

[mann1139]

25 to 23 is almost a 10% change.

What happens if you unplug the ATO?

What happens if you leave the new water outside the tank? Does the salinity drop?

 

[Randy Holmes-Farley]

It may just be testing error. If the total water volume is not changing a lot, then the salinity is not changing as much as you note.