Mg Dosing

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Hunter90 HD

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Good evening Reefers,

I am currently dosing Kh and Ca daily in respect to coral demands, but i am recently intrigued as to if i should be dosing Magnesium also.

So last week, my Mg started off at 1280 then at the end of the week it was 1240, should i be dosing to maintain 1280ppm ?

My target is 1280ppm but after reading some forums, i have found that many reefers do not bother dosing Mg as and only 2-part Ca and Kh.

Should i be dosing to achieve 1280ppm every day (daily dosing), the red sea recipe recommends targeting 1280.

What is everyone's general approach to Mg? Kh and Ca are too me the 2 of the 3 most important parameters to monitor.

Lee
 
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Dkmoo

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MG readings are notoriously inaccurate - especially the redsea tests where you have to add all these different reagents and drop liquids that any slight difference in the amount of ingredient you used is going to cause a swing. When i use that test and read the result, I always keep a +/- 40PPM margin of error in mind.

Best way to determine actual MG need is keep up a more frequent test in the same time for a few weeks (daily, every other day, etc..) and you should see a trend and average out the variances/inaccuracies. Then you will have a better picture on the actual MG consumption.

Chemically, mg consumption generally follows the same ratio as Alk/CA consumption in the below ratio. This is a very widely accepted observation based on how coral calcification works. If you find that your Alk/CA consumes similar to this ration, then your MG consumption should'n't be too far from it either:

2.8DKH per 18 - 20 PPM CAL per 1 - 0.5PPM MG.

EDIT: I personally autodose Alk/CA b/c my daily consumption is approx 1dkh/6ppm ca. i then dose mg manually every few weeks for 10 - 20 ppm depending on what the test results show. and adjust every couple of months if i see a trend of MG levels change from my weekly tests.
 
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Hunter90 HD

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MG readings are notoriously inaccurate - especially the redsea tests where you have to add all these different reagents and drop liquids that any slight difference in the amount of ingredient you used is going to cause a swing. When i use that test and read the result, I always keep a +/- 40PPM margin of error in mind.

Best way to determine actual MG need is keep up a more frequent test in the same time for a few weeks (daily, every other day, etc..) and you should see a trend and average out the variances/inaccuracies. Then you will have a better picture on the actual MG consumption.

Chemically, mg consumption generally follows the same ratio as Alk/CA consumption in the below ratio. This is a very widely accepted observation based on how coral calcification works. If you find that your Alk/CA consumes similar to this ration, then your MG consumption should'n't be too far from it either:

2.8DKH per 18 - 20 PPM CAL per 1 - 0.5PPM MG.

EDIT: I personally autodose Alk/CA b/c my daily consumption is approx 1dkh/6ppm ca. i then dose mg manually every few weeks for 10 - 20 ppm depending on what the test results show. and adjust every couple of months if i see a trend of MG levels change from my weekly tests.
Thank you Dkmoo,

I wasn’t aware Mg tests are notoriously inaccurate, seems that some people also say that Mg is topped up by their sea salt they use, and generally my water change is 1280 Mg.

I will continue to carry out these tests for Mg until I see a trend and then allow 40 +/- accuracy, thank you for this input.

I will invest in the Hanna testers at somepoint, all in my ever growing shopping basket :).

Lee
 

Dkmoo

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Thank you Dkmoo,

I wasn’t aware Mg tests are notoriously inaccurate, seems that some people also say that Mg is topped up by their sea salt they use, and generally my water change is 1280 Mg.

I will continue to carry out these tests for Mg until I see a trend and then allow 40 +/- accuracy, thank you for this input.

I will invest in the Hanna testers at somepoint, all in my ever growing shopping basket :).

Lee
Yeah if your consumption isn't high and have frequent water changes, mg should take care of itself.

I rarely water change and have pretty stocked bioload thats why I dose.
 
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Yeah if your consumption isn't high and have frequent water changes, mg should take care of itself.

I rarely water change and have pretty stocked bioload thats why I dose.
Makes sense, Red Sea recommends a 10% weekly change, but I tend to do 25% to 30% a week.

Would you say this is too much?
Could this do more harm than good?

I dose the new RODI water Kh levels to the same as the tank before water change so there is no dramatic shift in the water parameters, the Kh tends to swing .3 - .4 but stabilises back to 9 during a day or two.

Lee
 
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