So how much magnesium

["Mark Trueman" <mark.trueman at agfa_com>]

Ive determined through contact with numerous people that i may have a
magnesium deficiency in my tank.

My tap water comes out at

Calcium 134ppm
Magnesium 3.8ppm

Kh about 16 according to test kit

What i would like to know is what is my target ppm of Mg (i believe it has
a ratio with calcium) and how much epsom salts would i need to add to a 160
litre tank to get this ppm. I cant work out the equations, chemistry just
aint my thing. Maybe this ratio will increase my gh too much and make my
water too hard.

Any ideas

Mark