Salinity levels always dropping/stabilize at 30ppm?

[shootingstar_reef]

Hey reef folks

I have a 45g waterbox w/ sump. But I have the strangest thing always happen: the salinity of my system is constantly dropping. I am well aware that usually the salinity will increase due to evaporation and so my ATO has just RODI water, but any attempts at increasing my salinity are met with my system eventually dropping it to 30ppm (~1.022 sg) before I catch it again, and I'll do a water change. I'm measuring my salinity with a refractometer (yes I have calibration solution). I only have two fish, a wrasse and a black molly; and three hermit crabs. I also have some macroalgae and some coral: a euphyllia, a couple zoas, and gsp.

How is my salinity constatly dropping? Where is it going????

 

[BadSquishy]

Unless you have some crazy amount of salt creep somewhere.. my best guess would be testing error. Try a different calibration solution, and rinse the refractometer with distilled water and dry between every measurement.

Or.. do you have a skimmer? Do you empty it often?

 

[shootingstar_reef]

I typically rinse with RODI and dry with a small cloth between every measurement. I'll revisit this I suppose.

I don't have a skimmer.

 

[elysics]

There isn't a tiny leak somewhere,is there? Maybe look with a flashlight behind the tank and the sump for salt crystals

Otherwise, you say you have calibration solution, do you also use it often, preferably every measurement?

 

[arking_mark]

Salinity doesn't drop unless you are adding to or replacing some of the ASW. Since you have an ATO and haven't mentioned other additives or anything removing ASW but evaporation...it could be a leak. If you are testing the tank water and removing enough water...that could also the source of ASW removal.

 

[LeftyReefer]

The only way your salinity can drop over time is by replacing salt water with fresh water over time...
so if your salinity is really dropping, then your system is losing salt water some how... and it is constantly being replaced by fresh water from your ATO.

So check for a leak somewhere, or major salt creep. If that isn't happening, then I would suspect a testing error.

i'd check your water and then have your LFS check your water and see if you both are getting the same result, and go from there.

 

[Randy Holmes-Farley Verified Community Expert]

Skimmers remove salt water and slowly lower salinity.

 

[Garf]

Hey reef folks

I have a 45g waterbox w/ sump. But I have the strangest thing always happen: the salinity of my system is constantly dropping. I am well aware that usually the salinity will increase due to evaporation and so my ATO has just RODI water, but any attempts at increasing my salinity are met with my system eventually dropping it to 30ppm (~1.022 sg) before I catch it again, and I'll do a water change. I'm measuring my salinity with a refractometer (yes I have calibration solution). I only have two fish, a wrasse and a black molly; and three hermit crabs. I also have some macroalgae and some coral: a euphyllia, a couple zoas, and gsp.

How is my salinity constatly dropping? Where is it going????

Are you taking a jug full out, to test the water?

 

[shootingstar_reef]

There isn't a tiny leak somewhere,is there? Maybe look with a flashlight behind the tank and the sump for salt crystals

Otherwise, you say you have calibration solution, do you also use it often, preferably every measurement?

I don't normally use it every measurement, but if I doubt the measurement, I will check with calibration solution, and even RODI to make sure it's reading correctly.

Skimmers remove salt water and slowly lower salinity.

I don't have a skimmer, so I'll have to rule this out.

Are you taking a jug full out, to test the water?

I am not, I use a transfer pipette and take some out straight from the DT.

Thanks so much everyone - seems I need to check for a leak as well. Hopefully I find one because otherwise I have no idea what to do lol

 

[Pistondog]

Have lfs verify salinity.