# Epsom salts BP help



## murph (16 Jun 2010)

Is epsom salts BP (magnesium sulphate heptahdrate BP) bought from the chemist safe to use?


Thanks


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## ceg4048 (16 Jun 2010)

Hi,
   MgSO4 is MgSO4, but I have no idea what the BP stands for. Is that British Petroleum? Bi-Polar? Big Package? Maybe ask the chemist for clarification. Everything else about it is OK though.   

Cheers,


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## spider72 (16 Jun 2010)

It looks like name Epsom Salts is refering to heptahydrate form of magnesium sulfate:


> It is often encountered as the heptahydrate, MgSO4Â·7H2O, commonly called Epsom salt.


http://en.wikipedia.org/wiki/Magnesium_sulfate


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## murph (16 Jun 2010)

It's still safe in this form though right?

Ceg, don't have a clue! Could mean anything, I would know!


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## dw1305 (16 Jun 2010)

Hi all,


> The British Pharmacopoeia (BP) is the official collection of standards for UK medicinal products and pharmaceutical substances.


 new to me too. 

The only thing you need to note is that it is the heptahydrate form of magnesium sulphate, so it is MgSO4.7H2O (rather than the anhydrous MgSO4). You need to know the RAM of the elements to work out the percentages (via a periodic table <http://ukaps.org/forum/viewtopic.php?f=51&t=10037> or "James' Planted Tank calculator" <http://www.theplantedtank.co.uk/calculator.htm>)

So for Epsom salts it contains 24.3 + 32 + (4 x 16) . 7 x ((1 x 2) + 16) = RMM 246.3 so 24.3/246 so only 10% Mg rather than  24.3/120.3 = 20% it would contain if it was straight Mg SO4.

cheers Darrel


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## murph (16 Jun 2010)

Darrel I think my brain just melted!

Takes me back to high school chemistry when the teacher told me a mole was a number but refused to tell me what that number was! Wasn't important he said.


Should I double dose with this stuff then?


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## dw1305 (16 Jun 2010)

Hi all,
Just use James' calculator from the link, it is set up for "Epsom Salts".
cheers Darrel


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## chris1004 (18 Jun 2010)

Hi,

BP stands for British Pharmacopoeia and means that the Epsom Salts are produced to the pharmaceutically accepted grade for internal use, as laid out by the British Pharmacopoeia. If you are intending to use Epsom salt for internal use then this is the grade you need.

The BP grading is being phased out and is being replaced by a FCC grading.  This means it meets the specification laid down in the United States Food Chemicals Codex. 

Regards, Chris.


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## giwight (30 Jun 2010)

Hi,

I just got 2Kg of this (Epsom Salts) from eBay for only 99p plus Â£2.90 P & P included a manufacturer data sheet.

Here is the link if anyone is about to make a purchase.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=330381648470&ssPageName=STRK:MEWNX:IT

Hope this helps.

Regards

George Wight


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## andy-mu (11 Sep 2010)

I take it from The james calculator set up for heptahydrate form of magnesium sulphate compared to the UKAPS dosing guide for just MgS04 the only difference seems to be that epsom salts are in higher quantity's to achieve the ppm.

Does this sound about right?


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## dw1305 (12 Sep 2010)

Hi all,


> I take it from The james calculator set up for heptahydrate form of magnesium sulphate compared to the UKAPS dosing guide for just MgS04 the only difference seems to be that epsom salts are in higher quantity's to achieve the ppm.


 Yes use James' calculator, Epsom Salts will always be the heptahydrate form, as MgSO4 is unstable and will take in atmospheric moisture. To make anhydrous MgSO4 it is heated, to drive off the "water of crystallisation", and then kept in a dessicator. MgSO4.7H2O only contains about 10%Mg as you have to add 7H2O to the RMM calculation (see the formula earlier in the post).

cheers Darrel


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## andy-mu (12 Sep 2010)

Cheers Darrel. 

Your formula along with James calculator clears up the fact that Epsom is required in higher quantities. At least I know now. The thing is obviously Epsom is way cheaper than pure MgS04 on the aqua essentials website. Every saving is money available for other equipment. 

Should be converting to dry powders soon once my filtration is in place.


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