Magnesium sulfate (aka MgSO4/epsom salt)

[Gilles]

So i've been searching for a proper source of MgSO4, and came across epsom salt (since Wikipedia is referring to it)
Although the product is called epsom salt, it only contains 16% MgSO4, and i was wondering if that is enough to function as source for magnesium.
If not, what other products (commercially available) can you guys recommend?

 

[Seattle_Aquarist]

Hi Gilles,

I have used Epsom Salt as my source for Magnesium for a couple of year now. I typically use CaCl as my source for calcium. To keep my Ca:Mg ratio from getting out of whack, I dose 1 part CaCl to 1 part MgSO4*7 H2O which gives me about a 3.66:1 ratio of Ca:Mg.

 

[Jim Miller]

I think if you do the math the other 84% is the water of hydration.

jim

 

[Gilles]

Yeah i know, but i was wondering if 16% is a good 'percentage' of magnesium to work with (e.g. if i didn't require higher ratio's)

 

[hbosman]

What would be the recommended dosage of Magnesium in ppm? The report for our tap water says it has 8.8 ppm mg, 40 ppm calcium, calcium hardness is 102 ppm and total hardness is 137 ppm. Just wondering if I should boost the magnesium slightly or leave well enough alone.

 

[Gilles]

PPS pro (for my tank, 480 liter) tells me to add 1.2ppm Mg/week, but that is just info, not based on anything.. really

p.s. i am not doing pps (pro), just found the information there.

 

[Biollante]

If It Ain't Broke... Well You Aren't Trying

What would be the recommended dosage of Magnesium in ppm? The report for our tap water says it has 8.8 ppm mg, 40 ppm calcium, calcium hardness is 102 ppm and total hardness is 137 ppm. Just wondering if I should boost the magnesium slightly or leave well enough alone.

Hi,

You are just fine for most plants and critters, generally 3-5-ppm Magnesium is fine, 8.8 is not a problem.

!5-30-ppm Calcium is I think generally accepted, higher is not a problem, again for most flora and fauna.

Biollante

 

[hbosman]

Hi,

You are just fine for most plants and critters, generally 3-5-ppm Magnesium is fine, 8.8 is not a problem.

!5-30-ppm Calcium is I think generally accepted, higher is not a problem, again for most flora and fauna.

Biollante

Thanks very much!

 

[nipat]

Regular Epsom Salt is MgSO4.7H20 (Mg 9.86%, SO4 38.97%).
Your product sounds strange to me (16% MgSO4).

 

[Gilles]

It is 16% MgO, sorry. So i probably found the wrong product.
I now found magnesium sulfate heptahydrate (3$ for a kilo)

And the CaCl, should that be Calcium chloride hexahydrate (foodgrade) or just the normal stuff?

 

[Biollante]

Kieserite

Hi Gilles,

Sounds as though you purchased Kieserite, MgSO4.2H2O, which is a unstable.

All you have to do is open the Kieserite and in a fairly short time it will be Epsom salt.

CaCl2.6H2O is good, food grade I assume means it is purer, I use off the shelf CaCl2.2H2O so I do not see any need for extra expense if that is the difference.

In humid environments the CaCl2.6H2O probably makes more sense.

Biollante