Salinity does not remain constant.

[praton]

Good day. The salinity in my marine aquarium doesn't stay constant. Sometimes it fluctuates between 1024-1025. But when I look at the corals, they all look beautiful. There's no problem with the salinity meter.

 

[EnterName]

Iirc salinity can change quite a bit in natural coral reefs, which means 0.001 units (S.G., d20/20) aren't really something to worry about.

Depending on the used salinity meter you have to expect reading errors of that magnitude anyway, so even if it is operating properly. It may not be capable of providing readings precise enough to actually know if salinity is at 1.024 or 1.025.

Salinity doesn't really change on its own in a tank when keeping the volume consistent with RO/DI. Daily ups/downs could be explained with evaporation and a relatively "late" adjusting auto top off system, or reading errors that are caused by changes in certain water parameters throughout the day. Long term changes can be caused by a skimmer, roller mat, the daily dosed supplements (Calcium, Alkalinity, etc.), and more.

 

[Subsea]

I concur with Enter Name. Slight salinity fluctuations are normal: depending on when you measured salinity and when your ATO dosed.

Incidentally, Your corals look lovely.

 

[exnisstech]

Check the DT once every few weeks and you won't notice that swing . Personally I feel no need to test salinty on my tanks more often than that and have never felt the need to monitor them because it doesn't change enough to warrant it IMO
Your tank looks awesome so I wouldn't make a problem out of something that isn't one unless that's your thing.

One if my tanks that I rarely check salinity.

 

[Randy Holmes-Farley Verified Community Expert]

I agree that changes are ok, but the changes are either water level changes from evaporation replacement not being constant and exact, or just test error. :)