How to raise Mg alone?

[Peter Houde]

I was inspired by a recent thread to test Mg for the first time in years. I'd been led to believe that testing Mg was superfluous because levels would typically be high in salt mixes. I change ~25% water using Reef Crystals once a week (30g in a 125g tank with a fair amount but unknown displacement of substrate and rock). Ca is 455 and dKH 10.2. For years I'd used Purple-Up and Coral-Up until the latter was discontinued. Then, for months I used Purple-Up and Tropic Marin's K+/A- elements daily.Three days ago, I switched to All-in-Reef. All the while, I've maintained dKH as close as possible to 10.0 with only weekly testing using baking soda daily.

So...it turns out my Mg is 930. What product and how should I go about safely raising Mg alone?

 

[Garf]

I was inspired by a recent thread to test Mg for the first time in years. I'd been led to believe that testing Mg was superfluous because levels would typically be high in salt mixes. I change ~25% water using Reef Crystals once a week (30g in a 125g tank with a fair amount but unknown displacement of substrate and rock). Ca is 455 and dKH 10.2. For years I'd used Purple-Up and Coral-Up until the latter was discontinued. Then, for months I used Purple-Up and Tropic Marin's K+/A- elements daily.Three days ago, I switched to All-in-Reef. All the while, I've maintained dKH as close as possible to 10.0 with only weekly testing using baking soda daily.

So...it turns out my Mg is 930. What product and how should I go about safely raising Mg alone?

You measured magnesium in your new saltwater?

 

[Randy Holmes-Farley Verified Community Expert]

I don’t believe that value is accurate if the salinity is close to normal. 25% weekly RC will cause magnesium to be plenty high in any tank, unless the batch is grossly off.

FWIW, magnesium testing is fraught with bad results.

 

[Peter Houde]

I don’t believe that value is accurate if the salinity is close to normal. 25% weekly RC will cause magnesium to be plenty high in any tank, unless the batch is grossly off.

FWIW, magnesium testing is fraught with bad results.

I'll test the next batch of water I mix anew. In the meantime, do you think I should get a new test kit since the one I have is years old?

 

[Randy Holmes-Farley Verified Community Expert]

I'll test the next batch of water I mix anew. In the meantime, do you think I should get a new test kit since the one I have is years old?

My suggestion is:

https://www.reef2reef.com/threads/just-say-no-to-magnesium-testing-rmm-is-born.1017528/

 

[Dburr1014]

I'll test the next batch of water I mix anew. In the meantime, do you think I should get a new test kit since the one I have is years old?

The best kit is aquaforest. At least, it's the most accurate.


Post in thread 'Best magnesium test kit?' https://www.reef2reef.com/threads/best-magnesium-test-kit.1061986/post-12666875


I think not ever testing is a mistake. Yup, I disagree with Randy on this. Even if you test once a year, is better to know where you are than never know. Need to keep that baseline.

 

[Peter Houde]

I don’t believe that value is accurate if the salinity is close to normal. 25% weekly RC will cause magnesium to be plenty high in any tank, unless the batch is grossly off.

FWIW, magnesium testing is fraught with bad results.

By coincidence, I just stumbled upon the RMM link. OK, I get it. If my Mg truly is low, then it might be related to all the Ca I regularly dose for the coralline. I'll try re-testing Mg after a week of not dosing Ca to see if that makes a difference. If it does, then I'll likely stop dosing Ca for coralline, just stick with the water changes and All-for-Reef, and go back to not testing Mg for another several years. If it doesn't, then I'll go back to not testing Mg for another several years.

 

[Salty_Northerner]

I test mag once a month generally and it's not consumed very quick at all. I tested it 13 days ago and it was at 1380 and used red sea liquid magnesium to dose it to 1400, I tested today and it was 1380 so it's only dropping 20 points every 2 weeks. I'm not a huge fan of Red Sea products but when I was starting back up over a year ago I grabbed a bottle of it and it's actually pretty good stuff. That's just my honest opinion about it.