High Mg a problem?

[Nathaniellund17]

I do a 3 part dosing from BRS with soda ash for alkalinity, calcium chloride, and magnesium sulfate. My alkanlinity and calcium have always been stable at 8.9-9.0 for alkalinity and 440-450 for calcium (using Hannah Checker for alkalinity and Salifert test for calcium.) My Mg is also stable, but that is sitting at 1,500. My alkalinity I'm dosing 58 ml of soda ash per day, for calcium chloride, I'm dosing 35 ml per day, and for Mg, I'm dosing 1 ml once per week. Does this seem odd that my tank effectively isn't using any Mg?

 

[KrisReef]

Mg depletes very slowly relative to the other two. I have raised my Mg to 1500 in the past to deal with unwanted algae, but I try to keep it closer to 1320 -1400 day to day.

 

[Randy Holmes-Farley Verified Community Expert]

The test may not be accurate. What does it read in new salt water?

 

[Nathaniellund17]

The test may not be accurate. What does it read in new salt water?

That's a great question, next time I perform a water change, will check. Will get to this over the weekend.

 

[Nathaniellund17]

Mg depletes very slowly relative to the other two. I have raised my Mg to 1500 in the past to deal with unwanted algae, but I try to keep it closer to 1320 -1400 day to day.

Thanks for the reply. That makes sense that Mg depletes slowly. I suppose my question is does it make sense that my Mg is depleting this slowly (1 ml per week)? I'm thinking I might have to just stop dosing Mg - though I've heard from some people that just dosing a little doesn't harm, and could "jump-start" the system.

 

[Lavey29]

Thanks for the reply. That makes sense that Mg depletes slowly. I suppose my question is does it make sense that my Mg is depleting this slowly (1 ml per week)? I'm thinking I might have to just stop dosing Mg - though I've heard from some people that just dosing a little doesn't harm, and could "jump-start" the system.

Water changes typically suffice for magnesium depletion because it only depletes at 1/10th the amount of the other two. Maybe a little hand dose once a week but no more. I keep mine 1450 to 1500.

 

[Nathaniellund17]

Water changes typically suffice for magnesium depletion because it only depletes at 1/10th the amount of the other two. Maybe a little hand dose once a week but no more. I keep mine 1450 to 1500.

If I’m understanding this correctly, I’m dosing alkalinity at 406 ml per week… so I should expect to dose Mg at ~40 ml per week? To be dosing Mg at 1-3 ml per week and still have levels at 1500 seems odd.

 

[Nathaniellund17]

The test may not be accurate. What does it read in new salt water?

Just checked the Mg on a new salt mix of tropic Marin, and it came in at 1350. It would appear the test is working fine. Not sure how my Mg just is not depleting.

 

[JGT]

Mine does the same. Between 1450-1500 constantly. Never dosed. Stopped testing.

 

[gbroadbridge]

Just checked the Mg on a new salt mix of tropic Marin, and it came in at 1350. It would appear the test is working fine. Not sure how my Mg just is not depleting.

You tank is possibly just at the low end of consumption.

If you're doing water changes I'd simply not test it for a few months, if at all.

 

[Randy Holmes-Farley Verified Community Expert]

If I’m understanding this correctly, I’m dosing alkalinity at 406 ml per week… so I should expect to dose Mg at ~40 ml per week? To be dosing Mg at 1-3 ml per week and still have levels at 1500 seems odd.

What products are you using? The 1/10 comment is a ppm per day recommendation, not mL per day.

 

[Randy Holmes-Farley Verified Community Expert]

Just checked the Mg on a new salt mix of tropic Marin, and it came in at 1350. It would appear the test is working fine. Not sure how my Mg just is not depleting.

As noted above, it is extremely slow to deplete and water changes may maintain it since many mixes have high magnesium.

 

[Nathaniellund17]

What products are you using? The 1/10 comment is a ppm per day recommendation, not mL per day.

Okay, so 1/10 is not in relation to how much I’m dosing other products. I’m dosing BRS magnesium sulfate. Ultimately from the comments, it sounds as though I shouldn’t be concerned with how little I’m dosing. Really appreciate the replies. I’ll continue to monitor and not worry how little I’m dosing Mg.

 

[Randy Holmes-Farley Verified Community Expert]

Okay, so 1/10 is not in relation to how much I’m dosing other products. I’m dosing BRS magnesium sulfate. Ultimately from the comments, it sounds as though I shouldn’t be concerned with how little I’m dosing. Really appreciate the replies. I’ll continue to monitor and not worry how little I’m dosing Mg.

FWIW, magnesium sulfate is not a balanced recipe (I designed it, and there are improvements). Regardless, it is designed to be used with the other two parts, at a rate of 16% as much as the calcium part.

If magnesium is for sure higher than your target, it is ok to not use it, but it is also fairly likely the test is inaccurate and fir that reason, I don’t actually recommend mist folks even bother testing. Just fuse as prescribed:

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

 

[JustAnotherNanoTank]

Are you doing regular water changes?

They’re probably keeping up with mag and then you keep adding it.

But I know Jake Adams always favored high mag.

I keep mine above 1400.

 

[Lavey29]

Okay, so 1/10 is not in relation to how much I’m dosing other products. I’m dosing BRS magnesium sulfate. Ultimately from the comments, it sounds as though I shouldn’t be concerned with how little I’m dosing. Really appreciate the replies. I’ll continue to monitor and not worry how little I’m dosing Mg.

I dose 15ml of magnesium once a week in between monthly water changes. I dose 280ml of alk and 280ml of calcium per week in daily dosages. My mag stays 1450 to 1500 with coral pro salt. Magnesium depletes very slowly and if doing weekly water changes then no magnesium dosing is typically required.