Magnesium Dosage - is this right??

After confirming that I have bryopsis in my tank, I went and purchased a magnesium test kit, and the supplement. My first initial test showed my mag level at 1320ppm. The supplement I purchased (Magnesion) states that the solution works like this. 1ml of the concentrate will raise 1 gallon 26ppm of mag. My tank is 10 gallons, so it would only raise it 2.6ppm per 10 gallons. I'd like to get the tank to 1500ppm to start with to kill off the bryopsis so wouldn't that require 69.2ml (1500-1320=180/2.6=69.2) of concentrate? That seems like an awful lot of solution. Does this sound right?

 

I think your math is wrong here. you want to raise total calcium level 180 ppm

you have a 10 gallon tank, so you need to raise 180 ppm/10 gals = 18ppm per gallon.
so if 1 ML will raise one gallon 26ppm, you need to dose x to raise it 18ppm.

1ml/26ppm = xml/18ppm, solve for x and you get ~.7ml of solution per gallon in your tank.

so total, you should dose your 10 gallon tank 7ml.

 

wouldn't the 7ml dose only increase the 10 gallon tank 18.2ppm?

1ml = 26ppm in 1 gallon
1ml = 2.6ml in 10 gallons

7ml = (26ppm*7ml / 10 gallons) = 18.2ppm in 10 gallons

Seems like this should be really simple math as I assume concentrations are linear, correct?

 

You can actually use the calculator here at 3reef and it will tell you exactly how much you need.
3reef.com - Forums for coral reef aquariums, salt water fish, corals, inverts, protein skimmers, aquarium lighting and more - Calculators

just click additives at the top and put in your tank info.

 

O.k. let's keep it simple. First, you must go slowly when raising anything. Since 1 ml will raise 1 gal. 26 ppm you would need 10 ml to raise the ten gal. 260 ppm. Now, have you subtracted for rock and substrate? You may only have 6-8 gal of water volume.
My advice; Add 2 ml of Mag concentrate and wait a day and check your level, then add accordingly to arrive at the appropriate ppm. Remember, Cal will need to be at 450-500 ppm to hold the Mag at 1500 ppm.

 

I found that the Salifert Magnesium Powder also has the same ppm (26.42ppm/ml/gal) and that came out to 68.1ml of the solution to rise 180 ppm / 10 gallons. The source code for the calculator uses the following formula.

Added Concentrate ml = (Desired Mag ppm - Current Mag ppm) * volume in gallons / [PPM/1ml/gal]

Check
69.2308 ml = (1500ppm -1320ppm) * 10g / 26ppm

 

Looks like you have some good advice on dosing but I believe the only product that has been even anecdotally shown to work for this is Kent Marine Tech M unfortunately. If there are other success stories with other products I haven't read them. Something to look into.

 

It's a frag tank to there's really not much in it other than frags and a powerhead+heater, no sand. I'd say total water volume is 7-8 gallons.

I'll start slow with 5ml with a check after 12hrs.

 

That a Seachem Reef Advantage Magnesium.

You need to use magnesium sulfate not magnesium chloride. Most salts have an extremely low level of sulfate compared to NSW. I think it was something in the range of 1/10 or less.

 

The successful range is from 1600 on 2000 ppm.