Different salinity reading?

[Notsolostfish]

I have the BRS refractometer and i bought the brughtwell calibration solution for it adn calibrated it yesterday i checked my salinity and it was 1.026 and 1.024 hanna checker. Today i checked my salinity with the refractometer after checking calibration and its 1.027. I have the tunze osmolator 3155 ato. Whats going on? Is it normal to salinity to fluctuate?

 

[MnFish1]

I have the BRS refractometer and i bought the brughtwell calibration solution for it adn calibrated it yesterday i checked my salinity and it was 1.026 and 1.024 hanna checker. Today i checked my salinity with the refractometer after checking calibration and its 1.027. I have the tunze osmolator 3155 ato. Whats going on? Is it normal to salinity to fluctuate?

Every instrument has a margin of error - and I would say that 1.026 and 1.027 is within the margin of error. I personally am not a big fan of hanna checkers. You could always bring a water sample into an LFS and get a third reading - and see which one is closest. If you calibrated your BRS refractometer (perhaps do it again) - and the salinity (actually specific gravity) is consistently rising - that would be a more significant issue IMHO.

 

[littlebeard]

Have you changed anything in your system? Turned off or on your protein skimmer? Has the ato usage increased/decreased over the last day or so? Added any rock that could displace significant amount of water?

Silly question, could you accidentally put in salt water into your ato container?

How big is your system?

If you've ruled out all possibly increases in salinity via manual import then the only other possibility must be testing error. Can you recheck your salinity checking devices with your calibration fluid? (I'm assuming that is at 1.0264?) Could your calibration fluid be defective?


I've always found the manual refractometers extremely hard to read.

 

[Notsolostfish]

Have you changed anything in your system? Turned off or on your protein skimmer? Has the ato usage increased/decreased over the last day or so? Added any rock that could displace significant amount of water?

Silly question, could you accidentally put in salt water into your ato container?

How big is your system?

If you've ruled out all possibly increases in salinity via manual import then the only other possibility must be testing error. Can you recheck your salinity checking devices with your calibration fluid? (I'm assuming that is at 1.0264?) Could your calibration fluid be defective?


I've always found the manual refractometers extremely hard to read.

My RO chamber is at 7tds. Im assuming thats not salt and dust. And even if it was a drop of salt like drippled from my hand while working. It will skyrock more than 7 tds. And even if its drop of salt. It wouldnt push the salinity to 1.027

 

[MnFish1]

My RO chamber is at 7tds. Im assuming thats not salt and dust. And even if it was a drop of salt like drippled from my hand while working. It will skyrock more than 7 tds. And even if its drop of salt. It wouldnt push the salinity to 1.027

Agree - 7 TDS will not cause a specific gravity to increase. I would as also suggested - troubleshoot your ATO - to be sure its working (i.e. adding fresh water). BTW - are you dosing anything? Let's say calcium - or Bicarbonate? If you are - those can also raise specific gravity. Again - unless it's trending up consistently - I would not be overly concerned - especially if the tank looks fine. If you are concerned - take some of your saltwater out - and replace with RODI (depending on the size of your tank) For example I have a 140 gallon system - and my specific gravity had risen to 1.029 - I took out 2 quarts from the tank and added 2 quarts of RODI a couple times - then did that daily until I got back down to 1.026. Remember - that if the margin of error is +- .0005 (I don't know the margin of error of that instrument) - 1.026 and 1.027 are basically identical if the real SG is 1.0265.

One other thought did you rinse and dry your refractometer with RODI water after use it could be that you have some salt residue left after testing. Good luck - hope this helps

 

[Notsolostfish]

Agree - 7 TDS will not cause a specific gravity to increase. I would as also suggested - troubleshoot your ATO - to be sure its working (i.e. adding fresh water). BTW - are you dosing anything? Let's say calcium - or Bicarbonate? If you are - those can also raise specific gravity. Again - unless it's trending up consistently - I would not be overly concerned - especially if the tank looks fine. If you are concerned - take some of your saltwater out - and replace with RODI (depending on the size of your tank) For example I have a 140 gallon system - and my specific gravity had risen to 1.029 - I took out 2 quarts from the tank and added 2 quarts of RODI a couple times - then did that daily until I got back down to 1.026. Remember - that if the margin of error is +- .0005 (I don't know the margin of error of that instrument) - 1.026 and 1.027 are basically identical if the real SG is 1.0265.

One other thought did you rinse and dry your refractometer with RODI water after use it could be that you have some salt residue left after testing. Good luck - hope this helps

Im going to try and use RODI water to clean my refractometer. I was using RO water only to clean it. Ill retry tonight and see where im at could be residue.