Magnesium limits


4 May 2007
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I tested my parameters yesterday and found cal at 400, kh at 8dkh, and mag at 1300. Mag is on the high side.
My question is, is the mag too high?
If not where does Mag reach its maximum?
Alan what is your SG out of interest ?
alan what was the reading of your alk the last time you checked?

and what was it when you were using salt mix compared to when you where using NSW before?
All well within requirements...

Hey Alan,

1300 may SEEM much,as a number...especially if you're accustomed to lower test figures prior to this occasion.

You'll find sources : Salt Mix, Aragonite/Reactor Media, Additives positively lead to Magnesium gains...

All of which aid alkalinity/Calcium/pH stability for you!

BUT in context..
MATCHED to your ALK, Ca, sg.....all in check!!! :clover::clover:

Knowing your LARGE SYSTEM volume ,there are MANY ways it will be reduced... fairly quickly and easily.

~ precipitation ONTO chemically exposed Calcium Carbonate, recently added liverock, limestone, hydrocarbonate, crushed coral, coral sand, shells

~ Co-precipitation with an EXCESS of Calcium/alkalinity in solution.

~ Coralline algal formation

~ Tridacnid clam

~ other Molluscs

~ SPS, and LPS coral

~ Soft coral

~ Crustacea

You'll find NSW, and supposedly your Reef aquaria
Magnesium : Calcium RATIO in order of just over 3:1

Looking at Mg : Ca as 1300ppm : 400ppm , that's just peachy!!!

Your Magnesium presence is NOT TOO HIGH...far from it, in fact after Sodium/Chloride, Magnesium is 3rd most abundant ion in NSW.

PRACTICAL MAXIMA, are almost an impossibility, seeing magnesium is already quite high in concentration in normal seawater, so to significantly elevate it requires conditions that would rarely be encountered in oceans or even lagoons.
source: Magnesium in Reef Aquaria ]
by Randy Holmes-Farley

Based on facts from source cited below... that Mg >8000ppm levels are used to anaesthetise shellfish, and to assist in SHUCKING/opening Oysters (for the table)

It reaches a TOXIC LEVEL, when toxic effects are observed....and in your case it would be around 6 TIMES MORE....

"Oh Shucks! It's OYSTER!!!" ??!! :lol:

[FONT=Times New Roman, Times, serif][Magnesium — Part II ][/FONT]
[FONT=Times New Roman, Times, serif]by Craig Bingman Aquarium Frontiers April 1999

Simplistically....KEEP an eye on Ca:Mg Ratio, and if you maintain min Ca 350 mg/L, you should aim for min Mg 1050-1100 mg/L.

Again, I can't stress the importance accuracy plays(relatively speaking), in Ca vs Alk vs Mg test results.

It's no use if any 2 of them are obtained with BROAD-RANGE kits, while 3rd parameter is NARROW-RANGE....becomes untidy when you try to determine if all is well and no cause for concern...

So, relax...enjoy your reef

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gr8 explanation, thanks. Feel a lot better.
always great explanations from liauat!
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