Plummeting mag, high calcium?

[erniethedog]

I have been dealing with some strange test results in my tank over the last month. Everything is doing well, but over the last 3 weeks my magnesium took a nose dive from 1410ppm on 7/30 to 1100ppm today (8/26)

I measured my mag on both the Hanna checker and double checked with a new salifert kit. Both kits measured around 1100ppm

My other parameters are:
Calcium: 520-540
Alk: 8.4dkh
nitrate 4.2
Phosphate 0.05
Salinity 1.025

I have tested calcium with multiple test kits and it’s been consistently high for the last month (I am wondering if the salt just mixes high? I am using reef crystals).

I am dosing primarily kalk and supplementing with Red Sea alkalinity to try and rebalance my calcium.

My questions are:

1. Is a drop of 300ppm magnesium over the course of 3.5 weeks even possible?
2. Is it possible that the high calcium is influencing the magnesium test?
3. Recommendations for getting everything more balanced?

I am hesitant to try and bring up the mag number because I am unsure of whether this reading is accurate even with two tests reporting the same thing.

Thanks in advanced! I feel like I’m on a chemistry roller coaster right now

 

[Randy Holmes-Farley]

The magnesium drop is either test error or, unlikely, a big salinity drop. To deplete 319 ppm of magnesium would require consumption of more than 3,000 ppm of calcium.

Your calcium level is fine, and I’d ignore the magnesium for now. I recommend 400-550 ppm for calcium, and no, it is not itself causing the false mag result.

This has more:

Just say NO to magnesium testing: RMM is born

OK, this thread has been many years in the making, and I'm posting it here since folks in the chem forum are probably already tired of all the threads relating to problematic magnesium testing. I'm going to propose a method, let's call it the Randy Magnesium Method, or RMM for short. All good...

www.reef2reef.com

 

[rishma]

@Randy Holmes-Farley given the at least once daily threads seeking help with “magnesium problems” can I suggest making RMM mandatory reading and acknowledgement when someone signs in to R2R? Or at least just pin it to the top of the forum?

 

[Randy Holmes-Farley]

@Randy Holmes-Farley given the at least once daily threads seeking help with “magnesium problems” can I suggest making RMM mandatory reading and acknowledgement when someone signs in to R2R? Or at least just pin it to the top of the forum?

Lol

Maybe the latter. :)

 

[erniethedog]

@Randy Holmes-Farley, thanks for your quick response. I’ve definitely never heard this advice but it certainly fits with what I’m seeing in my tank right now. Certainly happy to save on mag test kits!