Magnesium dosing when using kalk

[rishma]

How much BRS magnesium liquid should I dose based on the amount of saturated kalk I am dosing?

mag supplement is BRS for general adjustments-7 1/4 c. Magnesium Chloride : 1/2 c. Magnesium Sulfate to make 1 gallon of solution.

I searched and read a couple threads on this but want to check to be sure I have this right.

I am going to start dosing saturated kalk. I want to add (separately) about the right amount of Mg. I will test Mg periodically but the tests are not super accurate so I’m trying to get the ballpark addition right and I can adjust as needed.

From a previous thread, @Randy Holmes-Farley posted: Magnesium is precipitated (e.g., into coral skeletons or abiotic precipitates) at a very rough rate of about 1.5 ppm magnesium for each 17.5 ppm calcium and 2.8 dKH of alkalinity.

If i dose 500 ml of kalk to 20 gallons of water, hamza’s calculator show I am adding 5.79 ppm Ca and 0.82 dkh Alk. Using the ratio to Ca above I need about 0.5 ppm Mg. Using the BRS calculator that equates to 0.8 ml of Mag supplement.

does that example seem right?

 

[blaxsun]

Bump.

 

[homer1475]

If your doing water changes, you have to consider how much MAG your adding with the new water also.

For instance I use IO which mixes up pretty high in MAG. Even though I dose about a gallon a month of ALK and CAL, my WC schedule keeps my mag in line. Therefore I do not dose it at all.

 

[rishma]

If your doing water changes, you have to consider how much MAG your adding with the new water also.

For instance I use IO which mixes up pretty high in MAG. Even though I dose about a gallon a month of ALK and CAL, my WC schedule keeps my mag in line. Therefore I do not dose it at all.

Good point. My salt mixes up near my target so If I am maintaining Mg right it should not have much impact for me.

 

[rishma]

I am sure some of you smart water Chemistry reefers can advise. Bump hoping for a reply

 

[Randy Holmes-Farley Verified Community Expert]

How much BRS magnesium liquid should I dose based on the amount of saturated kalk I am dosing?

mag supplement is BRS for general adjustments-7 1/4 c. Magnesium Chloride : 1/2 c. Magnesium Sulfate to make 1 gallon of solution.

I searched and read a couple threads on this but want to check to be sure I have this right.

I am going to start dosing saturated kalk. I want to add (separately) about the right amount of Mg. I will test Mg periodically but the tests are not super accurate so I’m trying to get the ballpark addition right and I can adjust as needed.

From a previous thread, @Randy Holmes-Farley posted: Magnesium is precipitated (e.g., into coral skeletons or abiotic precipitates) at a very rough rate of about 1.5 ppm magnesium for each 17.5 ppm calcium and 2.8 dKH of alkalinity.

If i dose 500 ml of kalk to 20 gallons of water, hamza’s calculator show I am adding 5.79 ppm Ca and 0.82 dkh Alk. Using the ratio to Ca above I need about 0.5 ppm Mg. Using the BRS calculator that equates to 0.8 ml of Mag supplement.

does that example seem right?

Many salt mixes start with high magnesium, and you may not ever need more, but dosing the amount you suggest seems reasonable as a general guide.

 

[rishma]

Many salt mixes start with high magnesium, and you may not ever need more, but dosing the amount you suggest seems reasonable as a general guide.

Thank you very much!

 

[Randy Holmes-Farley Verified Community Expert]

Thank you very much!

You're welcome.

Happy Reefing.

 

[GarrettT]

For instance I use IO which mixes up pretty high in MAG. Even though I dose about a gallon a month of ALK and CAL, my WC schedule keeps my mag in line. Therefore I do not dose it at all.

Old thread, but curious, is this in reference to the regular IO salt mix? My Mg is always low at 1,000 to 1,100. This has been tested against multiple salifert test kits through multiple salt bags.

 

[Randy Holmes-Farley Verified Community Expert]

Old thread, but curious, is this in reference to the regular IO salt mix? My Mg is always low at 1,000 to 1,100. This has been tested against multiple salifert test kits through multiple salt bags.

Perhaps your salinity is lower than 35 ppt by quite a bit.

Normal IO is usually much higher and I know the manufacturer specification at 35 ppt is much higher.

 

[GarrettT]

Looks like I need to break out the backup refractometer

 

[homer1475]

Old thread, but curious, is this in reference to the regular IO salt mix? My Mg is always low at 1,000 to 1,100. This has been tested against multiple salifert test kits through multiple salt bags.

Yup regular old purple box IO. I would definitely check that salinity! I've never had it mix that low, and I've been using it for ever.

 

[GarrettT]

I would definitely check that salinity! I've never had it mix that low, and I've been using it for ever.

Veegee STX-3 is measuring 1.026 and TM high precision hydrometer is 1.025. It's just strange that both Salifert Mg test kits could be wrong against multiple IO bags. When was the last time you guys tested? I'm adding about 250-300PPM in Mg and my CUC are unaffected, which would seem odd if the existing Mg levels were normal.

 

[homer1475]

Actually, I just tested a fresh batch out of a 160G bucket on sunday. 1350MG.

Have a new batch mixing right now, but out of the same bucket. So I'm going to assume it'll be the same, but I will definitely check it.

I check every batch I make. Nothings ever been weird, just my OCD.

 

[GarrettT]

Maybe it’s just the 50 gallon IO bags off Amazon . I may have to get a different test kit.

 

[homer1475]

I would think the bags would be more consistent, seeing as there would be no settling or stratification?

But yeah I've never used the 50G bags. Only the bucket, and 200G box, which in actuality is 4 50G bags. lol

 

[GarrettT]

Perhaps your salinity is lower than 35 ppt by quite a bit.

I would definitely check that salinity!

Sometimes it feels good to be wrong. My sg is actually 1.022. TM high precision was out the box defective. Calibration fluid was defective. Veegee just needed to be recalibrated with the right calibration fluid.

What's strange is how the defective calibration fluid instantly matched the TM and Veegee at 1.026. Seriously, what are the odds.... When I put RO water in the refractometer prism it showed 0.004. I should have looked more closely. The newly purchased calibration fluid confirmed it.

Appreciate the help on this. I have my first round of SPS corals coming in next week. This could have been a major let down.