Is my salinity off?

[Reef Stu]

I’ve been dealing with poor polyp extension on most corals, but not all. I’ve been racking my brain testing everything I can test, and it all seems very good. Last night I was watching a YouTube video on salinity and I’m sorry to say, the man in the video was making fun of the very way I was checking my salinity. I have two hydrometers (different brands), the type with the swinging arrows. They both say my salinity is about 1.025. I also had a refractometer I purchased three years ago and have never used. So I calibrated it with RODI water to 0 (I’ve ordered calibrating solution), and checked the salinity with it. It was 1.030! Do I bring down my salinity? Even though my test gear is two against one? The refractometer is made by Agriculture Solutions. I’m sure it’s not the best or most expensive brand... do I do nothing for two more days till I get the calibrating solution? I have recently added a black widow anemone and a gorgonian. The anemone looks great during the day but when the lights go out it has moved two nights in a row (the two nights I’ve owned it). The gorgonian has only 3/4 polyp extension.

 

[hijinks7]

hydrometers are awful. If 300 of them told me my water was 1.025 I'd trust the refractometer over them.

Slowly begin to remove salt water with RODI water and keep testing after waiting a few minutes for it to properly mix

 

[SDReefer]

If your corals aren't happy, I would start lowering the salinity. Make sure you recalibrate and test right when you get the calibration solution.

 

[EmdeReef]

I'd wait making changes until you can calibrate your refractometer. If you know anyone with a calibrated refractometer probably worth borrowing. Otherwise may be a worthwhile investment, you can get relatively cheap accurate refractometer for under $50... Also, not uncommon for an anemone to move or retract once the lights are off so I wouldn't think of that as an issue.

 

[Crabs McJones]

I’ve been dealing with poor polyp extension on most corals, but not all. I’ve been racking my brain testing everything I can test, and it all seems very good. Last night I was watching a YouTube video on salinity and I’m sorry to say, the man in the video was making fun of the very way I was checking my salinity. I have two hydrometers (different brands), the type with the swinging arrows. They both say my salinity is about 1.025. I also had a refractometer I purchased three years ago and have never used. So I calibrated it with RODI water to 0 (I’ve ordered calibrating solution), and checked the salinity with it. It was 1.030! Do I bring down my salinity? Even though my test gear is two against one? The refractometer is made by Agriculture Solutions. I’m sure it’s not the best or most expensive brand... do I do nothing for two more days till I get the calibrating solution? I have recently added a black widow anemone and a gorgonian. The anemone looks great during the day but when the lights go out it has moved two nights in a row (the two nights I’ve owned it). The gorgonian has only 3/4 polyp extension.

Your best bet would be to get some calibration fluid set at 35ppm and calibrate your refractometer with. While you can calibrate it with RO water, its not as accurate. With that being said I would slowly lower your salinity down to 1.026. best way to do this is to take a cup full of tank water out, and replace with RO/DI freshwater. Again do this slowly as you don't want to drop salinity to quickly.

Edit: With that being said I would slowly lower your salinity down to 1.026. best way to do this is to take a cup full of tank water out, and replace with RO/DI freshwater. Again do this slowly as you don't want to drop salinity to quickly. Do this after you've calibrated with the calibration fluid, forgot to mention that

 

[IslandLifeReef]

1.030 is high, but not overly dangerous. I wouldn't do anything drastic yet. Calibrating your refractometer with RODI water is OK, but calibrating it with solution known to be 35ppm is best. I don't think waiting 2 days until you get calibrating solution will hurt, especially since everything else in your tank has already adjusted to the higher salinity.

 

[ReefSapper]

You can always take some of your tank water down to your LFS and have them test for you as well just to compare against your reading. Keep in mind they rarely calibrate their refractometer correctly either but at least between the two readings you will have an idea and can start bringing the salinity down. Good luck!

 

[Reef Stu]

Thank you everyone!

 

[chipmunkofdoom2]

I would not do anything until you are sure you have an accurate test result. Acting on potentially incorrect information could make a bad situation worse. Calibrating refractometers with freshwater can give you incorrect results for various reasons. I would wait until you have the salinity standard, make sure your refractometers are reading correctly, test again, and go from there.

This is, of course, assuming you have refractometers. In your original post, you said you have two hydrometers. If that was not a typo and you do actually only have hydrometers, I would get a refractometer before continuing. It's likely that you did not order enough solution to calibrate a hydrometer.

 

[Reef Stu]

I would not do anything until you are sure you have an accurate test result. Acting on potentially incorrect information could make a bad situation worse. Calibrating refractometers with freshwater can give you incorrect results for various reasons. I would wait until you have the salinity standard, make sure your refractometers are reading correctly, test again, and go from there.

This is, of course, assuming you have refractometers. In your original post, you said you have two hydrometers. If that was not a typo and you do actually only have hydrometers, I would get a refractometer before continuing. It's likely that you did not order enough solution to calibrate a hydrometer.

The refractometer is what gave me the 1.030 reading. The two hydrometers gave a 1.025 reading. The man in the YouTube video was making fun of hydrometers. So that prompted me to use my refractometer. Sorry if I wasn’t clear.

 

[chipmunkofdoom2]

The refractometer is what gave me the 1.030 reading. The two hydrometers gave a 1.025 reading. The man in the YouTube video was making fun of hydrometers. So that prompted me to use my refractometer. Sorry if I wasn’t clear.

I understand now, thanks for the clarification. For what it's worth, there's nothing inherently wrong with measuring salinity with a hydrometer. They just have different caveats than refractometers: without taking special care when using them, it can be challenging to get consistent results. Because of this, many reefers prefer to measure salinity by means of refractive index or conductivity.

 

[EmdeReef]

The refractometer is what gave me the 1.030 reading. The two hydrometers gave a 1.025 reading. The man in the YouTube video was making fun of hydrometers. So that prompted me to use my refractometer. Sorry if I wasn’t clear.

You should make sure your refractometer is calibrated with a 35ppt standard before making adjustments. Old refractometer + RODI calibration could mean problems. In your case I wouldn't trust the refractometer over your hydrometers, but I also wouldn't trust a hydrometer.

+1 on not all hydrometers are made equal and some are even used in more professional applications. Tropic marin, I believe, still makes a pretty high quality one, the issues being around temperature correction.

 

[XNavyDiver]

I also had a refractometer I purchased three years ago and have never used.

I'm sorry, but I have just have to ask: why??

 

[Cory]

Your tanks salinity is similar to the red sea:

 

[Reef Stu]

I'm sorry, but I have just have to ask: why??

I assume you mean, why didn’t I use the new refractometer? Well because I had always used a hydrometer when I was in the hobby off and on from 1997-2006. I had mostly fish then with easy coral. So when I got back into the hobby again in 2015 I guess I just went with what I knew. I enjoy using the refractometer more now though [emoji1303]

 

[vetteguy53081]

Calibrate and compare. At least twice per year I take a water sample to my LFS and compare their reading with mine.

 

[madweazl]

I certainly wouldnt go changing anything. For what it's worth, the swingarm hydrometer I have matches my refractometer very closely. I'd certainly trust the hydrometer (especially two different ones that match) before a refractometer that was calibrated using RO/DI water.