Raising Magnesium

DRC Archive General Saltwater Discussion
1

Ok, so I’m NOT a regular monthly 20% water changing guy. More like 10% per month recently with maybe 20% every other month.

That said, I was running my tests today:

pH: 8.2
Ammonia: 0
Nitrite: 0
Nitrate: 0
Phosphate: 0
Calcium: 400 (I’m dosing to bring it up to 420 after magnesium is balanced with SeaChem Reef Advantage Calcium dry powder. Calculator says I only need to add 3.4tsp for that adjustment)
Alk: 10
Mag: 1275
Salinity: 1.025
Temp: 78
Gallons: 90 (After all the rock, plus the water volume in the sump, I assume I have 90gallons after a 90gal tank and a 15gallon sump. Maybe its a little less, but its what I put into the calculator)

So, I have the SeaChem “Dose” app on my iPhone, and I got the same results on a Mag calculator on ReefDigest.

Testing with the Salifert Magnesium test kit.

Volume: 90gal
Current Mag: 1275
Desired Mag: 1350
Calculator is using mg/l (ppm)
Using: Reef Advantage Magnesium from SeaChem (Ingredients: magnesium sulfate, sodium chloride. 80mg min. per 1 gram)

Result: Add 64teaspoons or 320.6grams

Thats 21.3 tablespoons. Which is pretty much, if not MORE, than the entire 300g (10.5oz) $8.29 bottle that I have. Which is supposed to treat 1,200gallons.

I mixed up some of the Magnesium with some RO/DI water and am slowly adding it to the tank. I just added about 2 cups worth and will monitor by checking the Mag again in the morning, add if necessary.

My last addition of Magnesium was 2/22/13. The calculator said I needed 77tsp. I added 10tsp, retested, and I was good.

What am I missing with these calculators, lol.

I’m using a SeaChem product, with a SeaChem calculator app.

2

Your Mg is fine, a good range is between 1250 and 1350, NSW is 1285. There is a lot more Mg in SW than Ca, so it will take a lot more supplement to raise it. What salt mix are you using? What is your SG? What are you using to measure it with?
If you’re using a “reef” grade of salt mix, i.e. Reef Crystals, I’d make sure the salinity is right by measuring it using a calibrated (@35ppt, using a calibration solution, not RO water) refractometer, or metering device. This will ensure you are adding enough Ca, Alk and Mg when you do your WC’s. With normal WC’s mixed to a salinity of 1.026, I’ve never had to add Mg, using this type of salt mix.

3

That sounds about right. each salt mix has a different leve lof Mg concentration, because, those salts are more expensive. and the mag chloride or sulfate are really low in Mg per gram of salt. they are MgCl.6H2O or MgSO4.6H2O molecules, which measns by weight, they are very little magnesium and mostly chlorine and oxygen and 6 water molecules or Sulfate and 6 water molecules. per molecule of Mg. If you use the periodic table you can figure the percentage by weight. in other words we have to add lots of MgCl (snow melt) or MgSO4(epsoms salt) to boost the Mg a little.

Actually the calculator and Randy Recipe give a ration of the two salts to add to keep the Chlorides and Sufates in balance while boosting Mg levels.

Hey, if you need any Mag Flake, ie: MgCl.6H2O , i got a bunch extra. I can bring you a gallon jug at the sept meeting. just mix with epsoms salt from the dollar store or drug store per the recipe.

4

I also used to use the seachem mag stuff until I found the recipe Kapt Ken gave you. WAY CHEAPER! same stuff. It does take a bit of the seachem to work. The seachem calcium advantage also has mag in it too, its supposed to maintain it when you get it where you want it. I found using bulk additives from places like Bulk reef supply (calcium) Shoprite (alk) and ebay/walgreens (mag) is just as effective and cost FAR less.