Ionic Imbalances Via Supplements

[kim]

Given a small mistake (wrong atomic mass for chlorine) in another thread, I settled down and did this properly. Might as well share it, having gone to the trouble.

We know that (eg) when we add calcium chloride to raise calcium, we inevitably also raise the chloride levels in our tanks. Since chloride is already so abundant in seawater, we usually reckon that it doesn't make much difference, and don't worry. But at what point should we become concerned, and instead make an effort to use a balanced additive instead ?

The following results might help.

I used the composition of seawater in Kaye & Laby, Tables of Physical and Chemical Constants 14th Edition, which probably isn't the latest analysis, but at least it's an authoritative source so that's one uncertainty nailed.

(i) Supplementing Calcium using Calcium Chloride

Raising calcium by 40 ppm raises chloride by 0.37 %.

(ii) Supplementing Alkalinity using Sodium Bicarbonate

Raising alkalinity by 2.8dKH / 1 meq / 50 ppm raises sodium by 0.21 %

(iii) Supplementing Magnesium using Magnesium Chloride

Raising magnesium by 100 ppm raises chloride by 1.53 %

(iv) Supplementing Magnesium using Magnesium Sulphate

Raising magnesium by 100 ppm raises sulphate by 14.51 %

Obviously, if you dose regularly, the effect is cumulative unless you also do water changes. Eg if you dose calcium chloride to raise calcium by 40 ppm per week, over 10 weeks your chloride will rise by 3.7 % - probably not a problem.

But if you have a magnesium deficient salt and just use magnesium sulphate (epsom salts, easy to obtain) to raise it by 300 ppm, you'd increase sulphate by 44 %. :o

Using magnesium chloride instead would raise chloride by only 5 %. :whistling:

Which is why most people recommend the chloride, of course.

Hth,

:)

kim

[hairyduck]

so why, out of interest does Seachems Reef advantage Magnesium (as recommended by Garf etc) only use a mixture of magnesium sulphate and sodium chloride?

[kim]

The Seachem site mentions only magnesium, chloride and sulphate, and their dosage instructions are consistent with a blend of standard magensium chloride and sulphate. If someone has mentioned sodium chloride, they were probably mistaken...it wouldn't make much sense.

:)

kim

[hairyduck]

I'm looking at the list of ingredients on the bottle sat next to me :-)

[kim]

:lol:

Then I'm stumped !

kim

[hairyduck]

:D maybe it's because they're using pure magnesium sulphate as apposed to heptahydrate that is used in epsom salts? Though that shouldn't make any difference to the amount of chloride, just the weight of the chemical needed to achieve 'x' rise in ppm

[uda]

AFAIK It's just the correct blend of magnesium chloride and magnesium sulphate.

I suspect it's just a simple typo, for Sodium read Magnesium. Can't think why you would put salt in there and the dosages do work out fine for a mag chloride/sulphate blend.

I feel a sarcastic email to seachem tech support coming on :evil:

[kim]

Originally posted by uda@Oct 18 2005, 13:48
I feel a sarcastic email to seachem tech support coming on :evil:
Naw, misleading packaging on a chemical ?

That's an opportunity to get a lifetime's supply of free supplements....

:)

kim

[Edit, it's definitely the hydrated salts, otherwise it would be twice as potent.]

[tuan]

(iii) Supplementing Magnesium using Magnesium Chloride

Raising magnesium by 100 ppm raises chloride by 1.53 %

(iv) Supplementing Magnesium using Magnesium Sulphate

Raising magnesium by 100 ppm raises sulphate by 14.51 %


C.Bingman did the same analysis ages ago somewhere and took it to a simpler method:-

Considering that Magnesium Chloride and Magnesium Sulphate have similar mol/kg ratio, you can basically use a ratio of 10:1.
ie. for every 10 measures (e.g. teaspoons) of Magnesium Chloride you use, use 1 measure of Magnesium Sulphate. This approximately keeps the Sulphate/Chloride balance close to NSW.

ps.
* Magnesium Sulphate = Epsom Salt, cheap as chips from Boots.
* Sodium Carbonate also cheap as chips from Boots, look for the indisgestion remedy section.

[simon garratt]

* Sodium Carbonate also cheap as chips from Boots, look for the indisgestion remedy section.

Might stop my maroon clowns from farting persistantly......... :D


Sorry, im not well at the mo.......... ;)

[uda]

Well I stand corrected (according to Seachem) it's not a typo :o Thank goodness I diddn't go for sarcastic.

Their answer is that by adding sodium chloride the product will increase both the sulphate and chloride ions in the correct ratio. It's an odd one but that's what the salt is doing in there.

According to Seachem they specifically exclude magnesium chloride from their products as it contains ammonia as a contaminant.

You learn something new every day!



edit:(according to Seachem)

[kim]

Andrew,

That's potty !

Let's say we raise Mg by 300 ppm using the sulphate alone. We then raise sulphate in the water by 44 %. :o :o

Are they implying that they bring the major ions into "balance" by increasing sodium and chloride by 44 % too ?

I doubt it (that would be a lot of table salt), and would have an amusing effect on salinity (up from 35 ppt to 48 ppt). :lol:

We also know that the potency of the Seachem (according to their instructions) is similar to that of a pure magnesium salt. Suggesting that the sodium chloride included isn't near the levels required to do anything useful about the sulphate imbalance (probably a good thing, given the salinity issues).

Looks like a "formula" developed to look clever, rather than to withstand analysis.

Plus, of course, magnesium sulphate is cheaper than magnesium chloride...... :ph34r:

kim

[uda]

You may think that, but I couldn't possibly comment :lol:

But I'm not going to disagree ;)

Who me? Sarcastic tongue in cheek comments-never :lol:

[lenny]

thanks for clearing that up guys. lenny

[jez]

Hi
I think one of the things seldom mentioned in all this chemistry is at what point does it go wrong, at what point is damage done and coral health and growth retarded.

The rate and volume people on this board buy calcium chloride as a cheap fix. You would expect to hear a few more horror stories. Of mysterious coral deaths etc.

regards jez

[kim]

Jez,

I think that we repeat pretty often that using substantial quantities of unbalanced additives like calcium chloride can be damaging in the long-term, and in this respect kalk/calcium reactors have advantages.

I understand your point, but these potions have their uses, which is I guess why you sell them ! Naturally, everything has to be used with care, but simple bulk chemicals from a chemical supplier are no more dangerous than, say, Kent's more expensively reckaged versions.

kim