Rising salinity levels

[hapeshkin]

Hi, this is my first post, so bare with me
I have a 29 gallon biocube that has been running for about a year now. For the past few months or so the salinity level is constantly rising. I am topping off with RO (not salt) water, and even going as far as replacing some salt water for RO water each day. We get the salinity level to 1.025 at night, and by the morning it's back at 1.030 (I know that's really high!!). What is going on in my tank that the salinity is rising so extremely?
Thanks for the help.
Hannah

 

[jdl513]

Based on what you said I can't think of a legitimate reason how that could occur.
For one it would take nearly 5 gallons of water loss through evaporation for salinity from a 29 gallon display to increase 0.005 sg in a single night.
That is more than most displays 10 times that size.

This makes me think it is an instrument issue.
Are you using a refractmeter or swing arm hydrometer?
If using a refractmeter are you reading it in the same light every time?

 

[jman9331]

I was having the same problem finally after awhile taking some saltwater out and adding fresh it stabilized itself out. currently holding at 1.024 when tank is completely filled.

 

[hapeshkin]

We use a refractometer. We take water from the top of the tank each time? Is that ok, or would I get a better reading from the middle of the tank?

 

[CastAway]

I have to calibrate my refractometer each use, using a calibration solution AND my RODI water. Doesn't sound like you're dealing with a meter issue, but worth mentioning perhaps.

 

[jman9331]

I've taken readings from the top and middle they both read the same

 

[mike007]

I think It Is a testing error there Is no way the salinity could change that much over night If you are using pure ro water to top off. My tank evaporates about 10 gallons a week and I top off with rodi water and salinity always stays at 1.026.

 

[Randy Holmes-Farley Verified Community Expert]

Yes, unless you evaporated the amount mentioned, the salinity simply did not rise. It also never varies through the tank.

Calibrate the refractometer each time.

Is it an ATC refractometer (automatic temperature compensation)?

Make sure you calibrate at the same room temp where you use it, and in the same type of lighting.

 

[Up2no6ood]

Make sure the refract. Is cleaned after use if not the water will evaporate and leave a salt film behind skewing your results.

 

[racin2438]

Yes, calibration of the refractometer is crucial. .....we do it every single time. ...Cuz the 1 time we don't we can have a error that creates a chain of events. ..

 

[Sangheili]

Any chance your tank is super-stocked and your dosing an insane amount of 3-part which is bumping up the sodium levels? About the only other thing I could think of that would cause SG to rise...

 

[Collier Branum]

Any chance your tank is super-stocked and your dosing an insane amount of 3-part which is bumping up the sodium levels? About the only other thing I could think of that would cause SG to rise...

Sangheili that is happening to me and I'm actually gaining a higher water level over night in my tank. I would guess the solution would be to balance out my tank water level. My salinity will rise 1.025 to 1.027 in maybe a day or to. Has gone a little higher the first time it did it.