Magnesium sulfate - balneotherapy home trial - help calculating additive amounts

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C

Caco

0
Dec 27, 2015
445
Hawera, Taranaki, New Zealand
Hi all
My partner has severe psorasis, its one of the reasons we follow TFP, the water actually seems beneficial to his skin, compared to a traditional chlorine pool system. Following advice from here I run my salt at 3000ppm which we like

Last year I added borax at 50ppm for extra water softening. We noticed during the season a big reduction in irritation, inflammation, cracking, bleeding, scaling and plaques. At the end of the last swim season we were down to a PASI (psorasis area and severity index) of 58, the lowest it had been in 30 years!!! This made me wonder if there was anything else I could do to reduce his symptoms.

So I have done a lot of research over our winter on balneotherapy (basically bathing in rich salt environments). All the medical research texts I could get my hands on showed no side effects and benefits in better PASI scores for 60%+ of patients. PASI score reductions that we could only dream of in fact. The most important salt has been identified as magnesium

The most common solution uses the following salt in a 5% solution:
46% MgCl2
2.2% CaCl
0.5% KCl
0.8% NaCl

Chemistry was just never my thing so I have no idea of how to calculate the above into a ppm or kg amount so I can add the magnesium. I was thinking of starting out at 25% of whatever the above would work out to and then up slowly if no problems were noticed, basically treating ourselves like lab rats, lol

My intention is to add the magnesium via magnesium sulphate at that is cheap and readily available to me. Is that a viable substitution?

Would adding magnesium interfere with any of our normal tests in any way

The guys at work will provide me with background magnesium levels for our water so I can take these into account

Any concerns re pool equipment?

Any thoughts appreciated on the chemistry






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I can get you an exact number in a little while (unless someone else comes along) as I'm getting the kids off to school and it's a bit hectic. It's likely going to be somewhere around 10lbs or so if epsom salt but I can do the exact math later.

If you have an SWG, pull it as the sulfates are bad for it. Mag chloride would be a better choice because it would not add sulfates and there's no telling if sulfates present would improve or worsen the psoriasis.

Hi magnesium levels will mess up the standard Taylor CH test as you need to add more R-0010 to get rid of the Mg interference.

I understand your situation as my wife has psoriasis (not nearly as bad though) and forever hounding her to get out on the the sun more. Now that we're done having kids, I want her to try PUVA therapy to see if that helps.
 
^This is just a question, not a declaration, but my understanding is that is if magnesium oxidizes in a pool it can cause black staining. Joyful, do you ave any thought n this? Sequestering would negate the benefit of the magnesium...
 
Okie dokie, I'm back (minus three kiddos....) -

Some data on molar masses -

MgSO4 ....................... 120.4 gm/mol
MgSO4 • 7 H2O ........... 246.5 gm/mol
MgCl2 ........................ 95.2 gm/mol
[Mg] ........................... 24.3 gm/mol
[Cl] ............................ 35.4 gm/mol
[SO4] ......................... 96.1 gm/mol

So, let's assume they measured their percentages accurately and you get the following -

46% x 5% = 2.3% ( x 10,000ppm/%) = 230ppm [MgCl2] = 230 mg/L of [MgCl2]

So that is the concentration of magnesium chloride in the solution. That can be put into [Mg] ion concentration units by simple math -

230ppm x (24.3/95.2) = 58.7ppm [Mg] or 58.7 mg/L of [Mg]

Most common Epsom salt found in stores is the heptahydrate, so MgSO4 • 7 H2O. Since the heptahydrate has a lot of crystalline water in it, you're going to need a lot more epsom salt by weight than you would magnesium chloride. So to figure that out, we do some more math -

58.7ppm [Mg] x (246.5/24.3) = 595.5ppm or 595.5 mg/L of MgSO4 • 7 H2O. Since your pool is 6,000 gallons (22,712.5L), that's going to require -

595.5 mg/L x 22,712.5L = 13,526,087.5 mg or 477.1 oz

477.1 oz / 16 oz/lb = 29.8 lbs

So, in order to achieve a similar level of magnesium ions in the water as they did with magnesium chloride, you're going to need to add 30lbs of magnesium sulfate to your pool.

To Kate's point that magnesium staining is possible, that is true, but highly unlikely. Magnesium ions have a very large solubility at pH values less than 10.2 (this is why one adds R-0010 to the CH test, to raise the pH) but, above a pH of 10.2 you will get the precipitation of magnesium hydroxide which can convert (slowly) to black magnesium oxide. But, the concentrations involved are enormous. Let me demonstrate that -

The dominant equation here is this -

Mg(OH)2 <=> Mg2+ + 2•OH-

The solubility product (Ksp) is defined as this -

Ksp = [Mg2+] [OH-]2

The Ksp for the above reaction is ~ 1.62 x 10-12. Magneisum sulfate additions would not change the pH at all (most magnesium compounds are pH neutral when dissolved in water) and so, if you assume that the pool water pH remains at 7.5, you get the following -

[OH-] = 10-pOH = 10-(14-7.5) = 3.16 x 10-7 M

Thus, the concentration (or molarity) of magnesium at maximum solubility would be -

[Mg2+] = Ksp/[OH-]2 = 1.62 x 10-12 / (3.16 x 10-7)2

[Mg2+] = 16.2 M

A 16.2 molar solution (that's 16.2 moles/liter) is an ENORMOUS concentration of magnesium. So, suffice it to say, you could not add enough epsom salt to be worried about magnesium scaling. However, if one had an SWG, you would have to be worried about magnesium scale forming inside the cell because an SWG cell pH can easily rise above 10.2.

Sorry for all the math, but it was necessary so others can check my super-advanced skills on the iPhone calculator....
 
Oh, and don't drink the pool water as that much magnesium will have a super huge laxative effect on your digestive system....
 
Thanks so much for the maths, really appreciate it! I dont have an swg, so that is not an issue and point noted re the staining
Laxative effect well known and accounted for, after all it is where the saying a dose of the salts comes from...

Thanks for the understanding Matt, it can be an awful condition to live with and I wish you luck with the UVA. We have tried UVB therapy unfortunately with little to no success, but know of others it has helped

One thing you may wish to try that eases the itching and showed some reduction for my partner was we switched to natural soap. My assumption is/was that sodium laurel sulphate had an irritant effect. Both my partner and I noticed our skin was a lot more hydrated as well

I think given the numbers above I will start with 2kg, a whopping $12 investment and see how it goes. The most effective study used the above solution for 15min of immersion 3x a week. I want to proceed really cautiously on this as we are in the pool a lot longer than the studies and I dont want to make his skin worse and because magnesium can be absorbed through the skin, dont want to end up on the toilet for the rest of the day
 
Caco said:
Also I wanted to say thanks for being so supportive and accepting of what I am going to trial. I know in other places I would have been dissed for being so experimental
:lovetfp:
Click to expand...

As long as you don't add copper or silver metals ions to your pool we promise to not make fun of you! (It's in the fine print in the Forum Rules.....you'll need a magnifying glass to see it...) :laughblue:
 
JoyfulNoise said:
Okie dokie, I'm back (minus three kiddos....) -

Some data on molar masses -

MgSO4 ....................... 120.4 gm/mol
MgSO4 • 7 H2O ........... 246.5 gm/mol
MgCl2 ........................ 95.2 gm/mol
[Mg] ........................... 24.3 gm/mol
[Cl] ............................ 35.4 gm/mol
[SO4] ......................... 96.1 gm/mol

So, let's assume they measured their percentages accurately and you get the following -

46% x 5% = 2.3% ( x 10,000ppm/%) = 230ppm [MgCl2] = 230 mg/L of [MgCl2]

So that is the concentration of magnesium chloride in the solution. That can be put into [Mg] ion concentration units by simple math -
....
Click to expand...
Matt, I don't know anything about balneotherapy, but I do like math, so... just a question about the above calculation -

2.3% ( x 10,000ppm/%) = 230ppm

I agree that 10,000/1,000,000 is 1%, so that looks right. What happened to the extra 0s in the multiplication, though? Why isn't the result 23,000 ppm? That would lead to a unreasonable-sounding amount of material to add to the pool, it seems (factor of 100 larger).

However, if I do a rough calculation of a 5% solution of a soluble material, just to get a ballpark idea -- that is, 5g to 100 ml of water (perhaps that should be 95 ml, but doesn't matter for ballpark), so 50g/l; multiply by 20,000 for something close to the size of the OP's pool to get 1,000,000g of the material; divide by 28 to get approx ounces - 35,700; divide by 16 to get lbs - 2230 lbs.

So that rough calculation suggests that there may actually be a factor-of-100 error...

I'm probably missing something really obvious, and thereby causing confusion in the OP's thread -- if so, I apologize!
 

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Nope. You're right. It's off by a factor of 100 (that's what I get for using my phone to do the calcs).

6000 gallons of water is about 50,000lbs of water. So 2.3% of that would be about 1,100 lbs in just a raw, back of the envelope numbers. So therefore 30lbs would definitely be in the ppm range not the % range.

The solubility calculation should be right because that's just based on the chemistry and not any particular chemical % value.

My apologies to the OP if I've confused the subject. I still think it's worth a try and maybe there can be some symptomatic relief at low levels.
 
Update on progress
Two weeks ago added 2kg of magnesium chloride to the pool. Over the next two days noticed no difference in pool or in feel of water or skin effects. About 5 days later added another 2 kg. Within about half an hour pool water turned yellow, kinda banana shade of yellow. Checked the ph and it was up at 8.2, measured two days previous at 7.4. Altered ph down to 7.0. Most of the water tint disappeared, leaving me with a pool that looked like it was filled with Fosters Radler beer :cheers: The next day some sort of sediment on the pool floor, felt gritty but it was very fine and after vacuuming it up the colour remained :(

Then life took me away from the pool, a 70hr work week, and a couple of trips to the ER at night for my partner and the pool got left to its own devices.

Imagine my surprise when I took the cover off the pool yesterday, thinking I was gonna have to do a partial drain and refill and it was back to clear as a bell blue. Pool had been sitting a few days at 0FC so bumped it up to 15 FC, did an OCLT, expected to see the yellow come back, but 0 loss of FC overnight and the blue remains :shock::kim:

Both my partner and I noticed a difference in water feel for the last two days, similar to the effects from adding salt. Skin also feels softer for longer after getting out of the pool than it did a couple of weeks ago, itchs less, but more of a residual feel, similar to dried sea water on the skin just not as intense, we didnt have that effect before.

Hesitant now to add more because I dont want to lose my pretty blue, almost clear water. Also dont want to increase the dried salt feel on the skin. For now I might leave it at that

Love to know how/why the yellow came and went, any ideas :scratch:
 
Did you add magnesium chloride or magnesium sulfate (Epsom salt)? Your original post said you were interested in Epsom salt.


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