High calcium and magnesium???

[steve_london_uk]

Hi all. So started my new RSR 350 a few weeks ago. I started with two bags of live sand, new dry rocks(Link here) , Fritz-Zyme Turbo Start, and iQuatics pro salt (Link here)

I have two clowns and a tang in there and a mixture of LPS and SPS frags.

Current levels are
Salinity: 1.027 (higher than I wanted which I need to address
PH: 8.2
Temp: 26c
Alkalinity: 6.4dkh (in process of raising with buffer)
Nitrates: 9.3ppm
Phosphates: 0.06ppm
Magnesium: 1800ppm!!!
Calcium: 550ppm!!

What could be causing the high MG and CA? I have tested the salt in fresh RO at 1.023 that I had laying around and levels were as they should as per the salt manufacturer... so why so high when I'm the tank?

- could it be because the salinity is higher?

- could there be something in the make up of the rocks that's raising them?

-Do I need to do a big water change to get them down or will it be ok to let them lower ok their own?

I look forward to any advice please. Thanks.

 

[ptrusk]

could it be because the salinity is higher?

That would be my assessment.

Let it come down on its own. You could replace some tanks water with RO but it's not the end of the world.

 

[ptrusk]

Oh and raising your alkalinity will tend to lower calcium reading and vice versa. Go slow to avoid precipitation but those levels are not really anything to worry about. Just keep dosing alk slowly. Personally, I keep mine between 8 and 9 DKH.


For your reference: http://reef.diesyst.com/chemcalc/chemcalc.html

 

[Randy Holmes-Farley]

How did you measure calcium and magnesium.

 

[steve_london_uk]

How did you measure calcium and magnesium.

With salifert tests. I did it there times as thought it was wrong and not working but when the secondary sample came out bang on I realised it was the tank.

 

[rishma]

A test kit I trust less than Calcium is magnesium. Some people get trustworthy results with calcium. I don’t feel like I do. Magnesium is always suspect. Not saying your results are wrong, but it’s a possibility to consider.

If it is real, I’d think perhaps it’s the salt mix if you didn’t dose anything. I am not familiar with that brand, but bad batches do happen. I suggest mixing up a batch of saltwater and testing it. That might give you some answers. If freshly mixed batch is also high, then either the salt batch is bad or the test kits are erroneous. You won’t know for sure. If the results are as expected, then we’ll have to look elsewhere.

With salifert tests. I did it there times as thought it was wrong and not working but when the secondary sample came out bang on I realised it was the tank.

 

[steve_london_uk]

I did do that already and test results were pretty much bang on to what they advertise. Around 450 Ca and 1360Mg.

 

[geologeek]

I did do that already and test results were pretty much bang on to what they advertise. Around 450 Ca and 1360Mg.

Then I think you have your answer, the salinity has pulled the levels higher and you should retest when you bring the salinity back into check.

That said the test results are not likely accurate in the first instance and just ballpark.

 

[Randy Holmes-Farley]

I did do that already and test results were pretty much bang on to what they advertise. Around 450 Ca and 1360Mg.

That was at 1.023?

Then I suspect the salinity measuring device is off, reading too low, because those should not be nearly that high at sg = 1.023, and at sg = 1.027, they will be 17.4% higher than that. Brings calcium to 528 ppm.

How are you measuring salinity?

 

[steve_london_uk]

That was at 1.023?

Then I suspect the salinity measuring device is off, reading too low, because those should not be nearly that high at sg = 1.023, and at sg = 1.027, they will be 17.4% higher than that. Brings calcium to 528 ppm.

How are you measuring salinity?

I have a refractometer. I'll check it's calibrated properly when I get home.

 

[Randy Holmes-Farley]

I have a refractometer. I'll check it's calibrated properly when I get home.

let's also discuss how to calibrate it. Using Ro/DI is usually not best.

 

[steve_london_uk]

Ahhhh lol. That's exactly how I was going to do it. I don't have any exact samples to test it against

let's also discuss how to calibrate it. Using Ro/DI is usually not best.

 

[Randy Holmes-Farley]

RO/DI is an immediate way to check it roughly, but a standard is a much better way as RO/DI may inherently be inaccurate (even when manufacturers say otherwise).

Refractometers and Salinity Measurement - REEFEDITION

Title photo by R2R member Rskillz By Randy Holmes-Farley Salinity is one of the most important parameters measured in reef aquaria. It controls not only the salt balance between an organism and its surrounding environment, but also the levels of a host of ions Read more here...

www.reefedition.com

To provide a standard for refractometers requires a solution whose refractive index is similar to normal seawater. Seawater with a salinity of 35 ppt has a refractive index of 1.3394. Likewise, the refractive index of different sodium chloride solutions can be found in the scientific literature. My CRC Handbook of Chemistry and Physics (57th Edition, Page D-252) has such a table. That table has entries for 3.6 and 3.7 weight percent solutions of sodium chloride that span the value for normal seawater. Interpolating between these data points suggests that a solution of 3.65 weight percent sodium chloride has the same refractive index as 35 ppt seawater, and therefore can be used as an appropriate standard (Table 5).

This 3.65 weight percent sodium chloride solution can be made by dissolving 3.65 grams of sodium chloride in 96.35 grams (mL) of purified freshwater. This recipe can be scaled to any appropriate size if suitable instruments are available (36.5 grams in 963.5 grams (mL) of water, 0.365 grams in 9.635 g (mL) of water, etc.).

 

[steve_london_uk]

RO/DI is an immediate way to check it roughly, but a standard is a much better way as RO/DI may inherently be inaccurate (even when manufacturers say otherwise).

Refractometers and Salinity Measurement - REEFEDITION

Title photo by R2R member Rskillz By Randy Holmes-Farley Salinity is one of the most important parameters measured in reef aquaria. It controls not only the salt balance between an organism and its surrounding environment, but also the levels of a host of ions Read more here...

www.reefedition.com

To provide a standard for refractometers requires a solution whose refractive index is similar to normal seawater. Seawater with a salinity of 35 ppt has a refractive index of 1.3394. Likewise, the refractive index of different sodium chloride solutions can be found in the scientific literature. My CRC Handbook of Chemistry and Physics (57th Edition, Page D-252) has such a table. That table has entries for 3.6 and 3.7 weight percent solutions of sodium chloride that span the value for normal seawater. Interpolating between these data points suggests that a solution of 3.65 weight percent sodium chloride has the same refractive index as 35 ppt seawater, and therefore can be used as an appropriate standard (Table 5).

This 3.65 weight percent sodium chloride solution can be made by dissolving 3.65 grams of sodium chloride in 96.35 grams (mL) of purified freshwater. This recipe can be scaled to any appropriate size if suitable instruments are available (36.5 grams in 963.5 grams (mL) of water, 0.365 grams in 9.635 g (mL) of water, etc.).

My LFS has 35ppt reference solutions so I'll check it with RODI tonight and then get some reference samples at the weekend to confirm.