Aquatic Plant Forum banner
1 - 7 of 7 Posts

·
Registered
Joined
·
426 Posts
Discussion Starter · #1 ·
I don't have a GH test kit around, so would someone please inform me how much MgSO4.7H20 (Epsom salt) is required to raise GH by X degrees in Y liters of water?

Thank you.
 

·
Registered
Joined
·
426 Posts
Discussion Starter · #3 ·
Thank you for the information Jay, but I am actually looking for how much of an increase in GH would X amount of MgSO4.7H2O have on Y volume of water.

I've done the math and wonder if someone could test it out. Add 1 teaspoon MgSO4.7H2O (~5.4 gram) to 10 gallon (~38 liter) of water and see if the GH will increase by 3 degrees. Scale down/up if you don't have a spare 10 gallon tank around. :D

Much appreciated.
 

·
Registered
Joined
·
542 Posts
Let's see.....

Isn't one german degree = 17.9 ppm? 17.9 ppm= 17.9 mg/liter. For gallons you would need 17.9 x 3.77 = 67.5 milligrams of Mg to raise one gallon 1 deg GH. Epsom salts are 9.9% Mg. So you would need 67.5/.099 = 681 mg of Epsom salts to raise 1 gallon of water 1 deg GH. Thats .7 gram Epsom salts to raise 1 gallon 1 deg GH.

Sounds like a lot! Can anyone check this?

Steve Pituch
 

·
Registered
Joined
·
426 Posts
Discussion Starter · #6 ·
Steve, you forgot to convert ppm CaCO3 to ppm Mg++.

1 german degree = 17.9 ppm CaCO3
17.9 ppm CaCO3 x .24 = 4.296 ppm Mg++ = 4.296 mg/liter Mg++
4.296 mg/liter Mg++ x 3.78 liter/gallon = 16.24 mg/gallon Mg++
16.24 mg/gallon Mg++ (246.476 mg Epsom salt / 24.305 mg Mg++) = 164.913 mg/gallon Epsom salt

That's .2 gram of Epsom salt to raise 1 gallon by 1 degree GH.

---

1 teaspoon Epsom salt = ~5.4 gram Epsom salt
 

·
Registered
Joined
·
542 Posts
CS,

OK, thanks for the correction. My little instruction booklet that came with the AP test kit says that GH is a measure of the total Mg++, and Ca++ positive ions in the water. So I was just including the ions, not the entire CaCO3 as the basis of the measurement. I guess I was taking the instructions too literally.

Thanks,
Steve
 
1 - 7 of 7 Posts
Top