Tropic Marin Magnesium?

[Kenmx10]

Has anyone been having low magnesium levels with the Tropic Marin Pro Reef salt? Im testing out at around 1215 using 2 different Salifert kits. Thx

 

[Pod_01]

I suspect measurement issue.

Have a read through this:

Thread 'Just say NO to magnesium testing: RMM is born'
https://www.reef2reef.com/threads/just-say-no-to-magnesium-testing-rmm-is-born.1017528/

Hope the link works.

 

[Kenmx10]

Thx. Looks like I missed that one.

 

[rishma]

I suspect measurement issue.

Have a read through this:

Thread 'Just say NO to magnesium testing: RMM is born'
https://www.reef2reef.com/threads/just-say-no-to-magnesium-testing-rmm-is-born.1017528/

Hope the link works.

It is interesting if the result is the same with 2 different kits

 

[Pod_01]

It is interesting if the result is the same with 2 different kits

At one point I had 3 mag test kits… Results were still all over the map.
I still have Mg additives from those days.

I been using TM Pro reef salt for long time, every ICP result I got the Mg is around 1350.

Alternative explanations can be that salinity is off… But that can be as confusing as measuring Mg sometimes !!!
:thinking-face:
But perhaps something to consider.

 

[rishma]

At one point I had 3 mag test kits… Results were still all over the map.
I still have Mg additives from those days.

I been using TM Pro reef salt for long time, every ICP result I got the Mg is around 1350.

Alternative explanations can be that salinity is off… But that can be as confusing as measuring Mg sometimes !!!
:thinking-face:
But perhaps something to consider.

I never test magnesium anymore, just RMM for my reef.

 

[Kenmx10]

It is interesting if the result is the same with 2 different kits

It was the average of the 2 test kits. One read 1200 while the other 1230. I figured the margin of era was close enough. But Im guessing not now, considering Tropic Marin claims between 1300-1400.

 

[rishma]

It was the average of the 2 test kits. One read 1200 while the other 1230. I figured the margin of era was close enough. But I guessing not now considering Tropic Marin claims between 1300-1400.

Those are close results. The question is, what’s more likely, two inaccurate magnesium test kits or TM salt being that far off? I’d personally assume the salt was made correctly, but I don’t test magnesium because I never trust the test result.

The salinity issue raised by @Pod_01 is a good point too. Could be a combination.

RMM has worked for many of us, verified by occasional ICP, and avoids this uncertainty. It’s not perfect, but better in my opinion.

 

[Kenmx10]

I always calibrate my refractometer and then compare it to my Milwaukee Digital Refractometer when doing a water change, so I feel confident the salinity was accurate at 1.026. Next water change ill test again with the Salifert kits just to see what they read.

 

[Kenmx10]

At one point I had 3 mag test kits… Results were still all over the map.
I still have Mg additives from those days.

I been using TM Pro reef salt for long time, every ICP result I got the Mg is around 1350.

Alternative explanations can be that salinity is off… But that can be as confusing as measuring Mg sometimes !!!
:thinking-face:
But perhaps something to consider.

Ill assume that your ICP tests are more accurate than my Salifert test kits and that Mag levels are closer to 1350 than 1215. Thank you.

 

[rishma]

I always calibrate my refractometer and then compare it to my Milwaukee Digital Refractometer when doing a water change, so I feel confident the salinity was accurate at 1.026. Next water change I’ll test again with the Salifert kits just to see what they read.

Are you using 2 different calibration fluids or the same fluids for both instruments?

I ask because I was using the same fluid for both, and my ICP showed my salinity was low. My choice was to either to assume my ICP was wrong, make my own diy calibration fluid, or buy a TM floating hydrometer which are known to be pretty accurate. I bought the floating hydrometer (black friday sale :)) and sure enough, my calibration fluid was off. My tank salinity was low and matched my ICP.

 

[Kenmx10]

I am not using the same calibration fluid with both units. I use 1.026 calibration fluid with the optical hand held unit , but the Milwakee Digital requires that you use distilled water only.

 

[gbroadbridge]

I am not using the same calibration fluid with both units. I use 1.026 calibration fluid with the optical hand held unit , but the Milwakee Digital requires that you use distilled water only.

Just to confuse you more, I have the Milwaukee device and when it reads 1.026 the water is actually 1.024. Which is within the +/- 0.002 device accuracy spec.

Personally I would assume the salt is correct and wait an ICP to confirm, but there would be no harm increasing your tank Mg by 100ppm if you wanted to.

 

[Kenmx10]

Just to confuse you more, I have the Milwaukee device and when it reads 1.026 the water is actually 1.024. Which is within the +/- 0.002 device accuracy spec.

Personally I would assume the salt is correct and wait an ICP to confirm, but there would be no harm increasing your tank Mg by 100ppm if you wanted to.

My Milwaukee unit is always consistently off by one point. If the solution is 1.026 it reads 1.025. I take that into consideration. Thx

 

[Randy Holmes-Farley Verified Community Expert]

I always calibrate my refractometer and then compare it to my Milwaukee Digital Refractometer when doing a water change, so I feel confident the salinity was accurate at 1.026. Next water change ill test again with the Salifert kits just to see what they read.

The Milwaukee claims an accuracy of +/- 2 ppt, which gives a range of 1225 to 1374 for a true 1300 ppm magnesium at 35 ppt.

 

[Randy Holmes-Farley Verified Community Expert]

I am not using the same calibration fluid with both units. I use 1.026 calibration fluid with the optical hand held unit , but the Milwakee Digital requires that you use distilled water only.

But you can check it’s accuracy .

 

[Kenmx10]

FWIW, I just mixed up a batch of Reef Crystals. Tested Mag using both Salifert test kits. They both read exactly the same. 1170 ppm. Seems, Either the salt is off or both test kits are off exactly the same amount. I calibrated my refractometer twice and took 2 sample readings . Both confirmed 1.026. The Digital Milwaukee confirmed the same. Odd that the magnesium tested low on both the Reef Crystals and the Tropic Marin Pro. It would be easier to blame the test kits if they weren't spot on with each other. Hard to believe both salts could be that far off though.

 

[gbroadbridge]

FWIW, I just mixed up a batch of Reef Crystals. Tested Mag using both Salifert test kits. They both read exactly the same. 1170 ppm. Seems, Either the salt is off or both test kits are off exactly the same amount. I calibrated my refractometer twice and took 2 sample readings . Both confirmed 1.026. The Digital Milwaukee confirmed the same. Odd that the magnesium tested low on both the Reef Crystals and the Tropic Marin Pro. It would be easier to blame the test kits if they weren't spot on with each other. Hard to believe both salts could be that far off though.

Add sufficient Mg to increase the salt water by 100ppm and test again.

 

[Pod_01]

I measure salinity with this:

As mentioned the Milwaukee has accuracy of +/- 2 ppt.


Maybe get different manufacturers Mg test kit, it is hobby after all :beaming-face-with-smiling-eyes: and playing mad scientist is part of the fun.
Also perhaps take 3 measurements and see if you get different value!!!

Good luck,

 

[Kenmx10]

I think the best thing to do is get a ICP test and see which numbers I can trust.