Salinity / Mag Issues (help)

[Hallowhead]

Howdy,

I'm having some sort of issue here.

I noticed my magnesium was dropping daily at excessive rates too which I've done my research indicating it's impossible for my mag to drop that much.

I then ordered an ICP test to confirm that my test kits were not the issue. My Mag / calcium and alk all tested in line with my salifert test kits.

The outlier was salinity which is still causing confusion for me.

I have two refractometers and the Hanna handheld salinity tester. My refractometer is calibrated with juice from BRS and the handheld is calibrated using Hanna tester calibration fluid. All three test kits show 35ppt however the ICP test came back at 31.5....

Someone help lol

 

[Pod_01]

From my experience drop in Mg is related to salinity decrease. My experience…

Since you are like me and collect all types of test devices and kits you should add this to your selection:

Once I got it I retired my refractometers. :beaming-face-with-smiling-eyes:

 

[Hallowhead]

From my experience drop in Mg is related to salinity decrease. My experience…

Since you are like me and collect all types of test devices and kits you should add this to your selection:

Once I got it I retired my refractometers. :beaming-face-with-smiling-eyes:

lol I was looking at one of these. It works well?

 

[Pod_01]

lol I was looking at one of these. It works well?

Yes that is my gold standard, I calibrate my GHL conductivity probe against it. All ICP lab results for salinity are always inline as well so I have high confidence in it.
Top it off it is easy to use and consistent.

After each use just clean it with tap or RO water so nothing is sticking to the glass.

 

[UMALUM]

Make sure your not testing warm water with cold instruments. Seems odd that 3 devices are showing similar results.

 

[Randy Holmes-Farley Verified Community Expert]

I’m wary of trusting any hobby brand salinity standards. I recommend either a science standard, or better yet, a diy using a decent scale.

https://www.reef2reef.com/ams/reef-aquarium-salinity-diy-calibration-standards.956/

 

[UMALUM]

Purchased in 1999 and still works like a charm.

 

[Hallowhead]

Purchased in 1999 and still works like a charm.

Grabbed one of these bad boys as a last ditch check. It's coming in at like a low 34ish ppt but not 31.5 like the ICP test. Obviously I'd like to believe the ICP test but now I've had 4 (granted hobby grade) test kits against one lab grade

 

[gbroadbridge]

Grabbed one of these bad boys as a last ditch check. It's coming in at like a low 34ish ppt but not 31.5 like the ICP test. Obviously I'd like to believe the ICP test but now I've had 4 (granted hobby grade) test kits against one lab grade

ICP does not directly measure salinity.

It may calculate salinity based on the elemental composition of the water, or they may be using an EC device.

Best way to check your measurement instrument is by making a DIY standard as Randy stated above.

 

[Hallowhead]

ICP does not directly measure salinity.

It may calculate salinity based on the elemental composition of the water, or they may be using an EC device.

Best way to check your measurement instrument is by making a DIY standard as Randy stated above.

It's on my list today !! Happy presidents day y'all !

 

[Hallowhead]

I followed this exactly, however using regular salt vs iodized salt and I can't even calibrate my refractometers to make them show 35pt. Could it be using salt vs iodized ? I used 2 liters exactly measured with a large measuring cup for liquids and used a 1/4 cup used for baking for the salt. I can try again measuring 73.1g instead using a scale I have but I want to confirm salt vs iodized doesn't matter.

That amount roughly corresponds to ¼ cup (73.1 g) of Morton's Iodized Salt dissolved into 2 liters (2000 g) of water (giving very slightly more than 2 L of total volume).

 

[Shirak]

regular table salt is fine. Doesn't need to be iodized. If you have a decent electronic scale I would use that. I reduce the recipe and use 3.65g into 100ml(g)

edit I have the decimal in the wrong spot sorry.. correct now

 

[Shirak]

Sorry @Hallowhead I had the decimal in the wrong spot. Correct now 3.65g table salt 100g RODI H2O

 

[Hallowhead]

I don't get why my prior mix per Randy's directions resulted in crazy high salinity water though

 

[Randy Holmes-Farley Verified Community Expert]

I don't get why my prior mix per Randy's directions resulted in crazy high salinity water though

I don’t know what happened, but iodized vs not is insignificant.

 

[Hallowhead]

I don’t know what happened, but iodized vs not is insignificant.

Mixing up another batch based on 100ml and 3.65g or salt. Standby

 

[Hallowhead]

Okay so after making two more batches to just confirm, my brs refracto juice appears to be about a point or two high which makes my swing arm about two points low.

My tank is within acceptable range and the ICP test was without a doubt wrong, which is the most concerning. Tank water is 34ppt and ICP claimed 31.5ppt

 

[Randy Holmes-Farley Verified Community Expert]

Okay so after making two more batches to just confirm, my brs refracto juice appears to be about a point or two high which makes my swing arm about two points low.

My tank is within acceptable range and the ICP test was without a doubt wrong, which is the most concerning. Tank water is 34ppt and ICP claimed 31.5ppt

Sounds good. :)

 

[Hallowhead]

Sounds good. :)

Thank you for the help !

 

[gbroadbridge]

Okay so after making two more batches to just confirm, my brs refracto juice appears to be about a point or two high which makes my swing arm about two points low.

My tank is within acceptable range and the ICP test was without a doubt wrong, which is the most concerning. Tank water is 34ppt and ICP claimed 31.5ppt

FWIW, the local lab that does the Triton ICP always gives me nonsense values for Salinity (at least 2-3ppt too high)

No idea why, I just ignore it.