best magnesium levels

[cooper]

What do you all think is the best magnesium level for a reef tank? Thanks.

 

[parsonsaj]

Isn't the rule of thumb approximately 3x your calcium level? I think somewhere in the 1200-1300 level is about right---at least that's what I've been told.

 

[drnecropolis]

I keep mine around 1450 or so..

 

[dannybradley]

You should base it on your calcium and alkalinity. Here's a chart I made based on NSW levels(rounded to the nearest decimal):

1dKH - 59ppm Ca - 184ppm Mg
2dKH - 118ppm Ca - 368ppm Mg
7dKH - 413ppm Ca - 1288ppm Mg
8dKH - 472ppm Ca - 1472ppm Mg
9dKH - 531ppm Ca - 1656ppm Mg

You don't need to chase these numbers to perfection. I'd have my Mg high if anything, my alkalinity a little high for pH stability, and my calcium close to NSW, so- 8-9dKH, Calcium 420-450, Mg 1300-1500.

 

[ouling]

I go for 1500ppm just so I don't have to worry about it in the near future. Better to be over 1400 than below it in my noob opinion.

 

[acroholic]

DannyBradley;303537 wrote: You should base it on your calcium and alkalinity. Here's a chart I made based on NSW levels(rounded to the nearest decimal):

1dKH - 59ppm Ca - 184ppm Mg
2dKH - 118ppm Ca - 368ppm Mg
7dKH - 413ppm Ca - 1288ppm Mg
8dKH - 472ppm Ca - 1472ppm Mg
9dKH - 531ppm Ca - 1656ppm Mg

You don't need to chase these numbers to perfection. I'd have my Mg high if anything, my alkalinity a little high for pH stability, and my calcium close to NSW, so- 8-9dKH, Calcium 420-450, Mg 1300-1500.

Hi Danny,
What is the basis for an almost 1700 ppm magnesium at 9dKH? What would be the level for 10 or 11dKH? Those mag numbers seem rather high. I would think the only reason to go that high with magnesium would be if you are playing around trying to prevent algae growth. Any mag level higher than NSW seems a waste of money in supplements to me, particularly because of amount of magnesium required to supplement.

Reason I ask is the the Randy Holmes Farley series of beginner reef chemistry articles recommends target levels for natural seawater: 7-11 dKH alk, 380-450 ppm calcium, and 1250-1350 ppm magnesium, regardless of your alk or calcium level.

Cooper, you should read these 4 articles. They are located at Reef Central in the Reef Chemistry Articles Archive, and provide a sound basis for understanding Reef Chemistry:

The "How To" Guide to Reef Aquarium Chemistry for Beginners

The “How To” Guide to Reef Aquarium Chemistry for Beginners, Part 1: The Salt Water Itself
http://reefkeeping.com/issues/2007-03/rhf/index.php"><span style="color: #000088">http://reefkeeping.com/issues/2007-03/rhf/index.php</span></a>

The “How To” Guide to Reef Aquarium Chemistry for Beginners, Part 2: What Chemicals Must be Supplemented
[IMG]http://reefkeeping.com/issues/2007-04/rhf/index.php"><span style="color: #810081">http://reefkeeping.com/issues/2007-04/rhf/index.php</span></a>

The "How To" Guide to Reef Aquarium Chemistry for Beginners, Part 3: pH
[IMG]http://reefkeeping.com/issues/2007-05/rhf/index.php"><span style="color: #000088">http://reefkeeping.com/issues/2007-05/rhf/index.php</span></a>

The “How To” Guide to Reef Aquarium Chemistry for Beginners,
Part 4: What Chemicals May Detrimentally Accumulate
[IMG]http://reefkeeping.com/issues/2007-09/rhf/index.php"><span style="color: #000088">http://reefkeeping.com/issues/2007-09/rhf/index.php</span></a>

And here is a Reef Chemicals Calculator which is very useful for calculating volumes/amounts of supplements:

Reef chemicals calculator
[IMG]http://home.comcast.net/~jdieck1/chem_calc3.html"><span style="color: #000088">http://home.comcast.net/~jdieck1/chem_calc3.html</span></a>

Dave

 

[derek_s]

I run my KH,CA,MG at 8/500/1400 currently. I am shooting for a higher Mag, maybe 1600 or so. I'm not sure where I got those numbers, maybe fro one of Danny's previous posts.

I have just been adding epsom salt every few weeks and it is climbing pretty well. A few months ago it was ony 1100. I also have some of the Brigthwell Magnesium for calcium reactors that I need to add someday.

 

[dannybradley]

Acroholic;303650 wrote: Hi Danny,
What is the basis for an almost 1700 ppm magnesium at 9dKH? What would be the level for 10 or 11dKH?

target levels for natural seawater: 7-11 dKH alk, 380-450 ppm calcium, and 1250-1350 ppm magnesium, regardless of your alk or calcium level.

If you read my full post you'll see the levels that I personally recommend. I suggested Mg high 1400, dKH a little high 8-9, and calcium close to NSW 420. I'm not advocating keeping levels far outside of NSW, but that chart is ionic harmony in your tank for the major skeletal builders.

To stay in ionic harmony, you would have to follow my chart. It's fool hardy to jack up any one of those levels far outside of the chart I had listed because you'll experience high precipitation rates and because your coral is still going to use it in the same ratio, meaning that if you have raise one level high(dKH11) your corresponding level(calcium) will always be more deficient, limiting coral growth. The chart proves how silly it is to try to keep highly elevated levels. I didn't include Salinity in that chart, but it would increase in the same manner.

If your magnesium, calcium, and alkalinity are not reasonably inline, you're going to stress your coral, waste money on dosing, and kill your pumps with precipitation and number chasing.