Alk calc and mag

[unclepregs]

While I don’t know how to make a reference with table salt, my own method simply uses regular saltwater salt, as you can also cross-reference it with Alk, Ca and Mag tests as well.

Yeah I think my refrac is pretty spot on through calibration and my LFS also double checking it. I am going to mix my salt around then make a batch of water and test it to see what I get. I do know my ALK was testing around 8 which was perfect but did not check anything else out bc my params were stable and good. It was just this last set of testing where my calc was 340-350 and mag was 1080. Had my LFS confirm this to make sure I was testing correctly and everything is low for some reason. I figured having low mag created some precipitation causing alk and calc to drop.

That is why I was wondering if the salt checks out and everything is good, should i dose to get back up and check to see if it stabilizes or do 2-3 50% water changes to get it back up. I am thinking of dosing each one so I do not crash my nitrates bc the tank seems to be running pretty well at the moment.

 

[Randy Holmes-Farley]

Even at a sg of 1.025, it is low. And it may be even lower and still be accurately calibrated since precision is not high on most refractometers.

Raising it to 35 ppt (sg = 1.0264) from sg = 1.025 will boost them as follows:

Alk 6.1 --> 6.44

Calc 340 --> 360

Mag 1080. --> 1140

 

[Randy Holmes-Farley]

Try your own kits on new salt water made to your salinity. It almost certainly will be low, and most likely due to low salinity.

 

[DanyL]

Yeah I think my refrac is pretty spot on through calibration and my LFS also double checking it. I am going to mix my salt around then make a batch of water and test it to see what I get. I do know my ALK was testing around 8 which was perfect but did not check anything else out bc my params were stable and good. It was just this last set of testing where my calc was 340-350 and mag was 1080. Had my LFS confirm this to make sure I was testing correctly and everything is low for some reason. I figured having low mag created some precipitation causing alk and calc to drop.

That is why I was wondering if the salt checks out and everything is good, should i dose to get back up and check to see if it stabilizes or do 2-3 50% water changes to get it back up. I am thinking of dosing each one so I do not crash my nitrates bc the tank seems to be running pretty well at the moment.

Since we all think it is a salinity problem, I would tackle it first before fixing any values, because if you do this right now and later on find out your salinity was indeed low it would be another thing that needs fixing.

 

[unclepregs]

Try your own kits on new salt water made to your salinity. It almost certainly will be low, and most likely due to low salinity.

Okay cool, I will make a batch of saltwater to match my tanks salinity and test the params. Everyone is talking about the salinity and refracs are not that accurate, what would you use to check it? Hydrometer?

Even if it is my salinity and I raised it to 35ppt, you said it would only raise alk up to 6.44 which still seems low. I will make some salt tonight and check back with everyone on whats going on. appreciate all the help.

 

[Randy Holmes-Farley]

Okay cool, I will make a batch of saltwater to match my tanks salinity and test the params. Everyone is talking about the salinity and refracs are not that accurate, what would you use to check it? Hydrometer?

Even if it is my salinity and I raised it to 35ppt, you said it would only raise alk up to 6.44 which still seems low. I will make some salt tonight and check back with everyone on whats going on. appreciate all the help.

The concern is that salinity may be much lower. I'd make a salinity standard to calibrate the refractometer. Buying can work too, but then you are trusting some unknown person to make it.

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

Do-it-yourself Refractometer Standards

In a previous article I described how to make a do-it-yourself refractometer standard matching 35 ppt seawater, and I will just summarize that recipe here.

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).

his 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.).

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

 

[unclepregs]

The concern is that salinity may be much lower. I'd make a salinity standard to calibrate the refractometer. Buying can work too, but then you are trusting some unknown person to make it.

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

Do-it-yourself Refractometer Standards

In a previous article I described how to make a do-it-yourself refractometer standard matching 35 ppt seawater, and I will just summarize that recipe here.

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).

his 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.).

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

wow, this article is super informative that you wrote. You are saying you want me to make my own calibration solution to calibrate my refrac essentially to make sure its dialed in correctly?

 

[Perthegallon]

are you using red sea salt

 

[unclepregs]

are you using red sea salt

Yes the blue bucket

 

[Randy Holmes-Farley]

wow, this article is super informative that you wrote. You are saying you want me to make my own calibration solution to calibrate my refrac essentially to make sure its dialed in correctly?

Yes, lots of folks do.

 

[Naekuh]

How long do the DIY calibration solution stay good for?

I was actually thinking of making my own, but was just too lazy to do so, and always bought it.

 

[Randy Holmes-Farley]

How long do the DIY calibration solution stay good for?

I was actually thinking of making my own, but was just too lazy to do so, and always bought it.

If they are closed and do not evaporate, longer than you will have a reef tank.

 

[Perthegallon]

Yes the blue bucket

I just got a bucket that had normal levels but the alk was 7 huge defect

 

[Randy Holmes-Farley]

I just got a bucket that had normal levels but the alk was 7 huge defect

Are you being sarcastic? Red Sea only claims it to be 8 dKH.

 

[Perthegallon]

Are you being sarcastic? Red Sea only claims it to be 8 dKH.

sorry should have specified it was the black bucket that is supposed to be 12

 

[Randy Holmes-Farley]

sorry should have specified it was the black bucket that is supposed to be 12

Ah, ok. The Coral Pro is very susceptible to calcium carbonate precipitation, which lowers alk a lot.