Strontium

lduncan

Member
Just a question about strontium dosing.

I know that strontium chloride is the most common strontium additive.
However, i've found it difficult to track down here (outside of pre-prepared commercial reef supplements which are pretty expensive).

I have managed to find a source of strontium hydroxide. I guess the question is does it have any properties which may cause problems?

I would guess it would undergo similar reactions as kalk, providing a source (albeit tiny) of alkalinity, and of course strontium ions instead of calcium.

Can anyone see any problems with using this?

Layton
 

Boomer

Bomb Technician (EOD)
Premium Member
I'm glad you have brought this up. I have often wondered why I have never seen a post on it before that I can think of. I keep forgetting to bring it up. I see no issue other than what you have already stated, other than it is more reactive. Have you read Randy's Sr article ( nothing about hydroxide though ) ?
 

lduncan

Member
Glad I brought up strontium, or strontium hydroxide in particular? There must have been a few discussion on strontium here before?

Yip, i've read Randy's article. It raises a lot of questions and provides a couple of answers. Looks like there are still a lot of unknowns.
 

lduncan

Member
Just had a thought on why chloride might be more common than hydroxide, at least in commercial preparations. Strontium hydroxide is obviously a reasonably strong alkali and caustic, so maybe it's handling and transport safety related.
 

Boomer

Bomb Technician (EOD)
Premium Member
Yes, I meant Strontium Hydroxide. I figured you already knew it was more reactive and a caustic but so is Calcium, Magnesium and Sodium ( the most caustic of all ) hydrox. and they have all been brought up here

Lot of Sr discussion but I could find none on the hydrox form
 

Randy Holmes-Farley

Reef Chemist
Premium Member
I'm not convinced that we need strontium additives in any form, but that said, strontium hydroxide is OK. The differences from the chloride would be:

1. A small boost to alkalinity. A 5 ppm boost in strontium will boost alkalinity by 0.1 meq/L (0.3 DKH).

2. 1. A small boost to pH. A 5 ppm boost in strontium will boost pH by very roughly 0.1 pH unit.

3. While strontium hydroxide is more soluble than calcium hydroxide, you may still need to add it to a fairly large amount of fresh water to dissolve it. 1 part of anhydrous strontium hydroxide will dissolve in about 50 parts of Ro/DI water.

4. If you do not dissolve it first, you risk having undissolved solids land on delicate organisms, and may also precipitate local precipitation of CaCO3 (similar tot he risks of dosing milky limewater).

These articles have more on strontium and the latter talks about the solubility of strontium hydroxide:

Strontium and the Reef Aquarium
http://www.advancedaquarist.com/issues/nov2003/chem.htm

Magnesium and Strontium in Limewater
http://www.advancedaquarist.com/issues/dec2003/chem.htm
 

Boomer

Bomb Technician (EOD)
Premium Member
latter talks about the solubility of strontium hydroxide

I looked there last night too and I still can not see anything on strontium hydroxide. I still can not find it. Do I need new glasses :lol:
 

lduncan

Member
I guess the same approach could be taken with strontium hydroxide, as with kalk, by adding acetic acid to increase the solubility too?

Seen strontium acetate has a solubility of 369g/L ? Compared with hydroxides 20g/L.
 

Randy Holmes-Farley

Reef Chemist
Premium Member
Yes, adding vinegar will boost the solubility. :)

I looked there last night too and I still can not see anything on strontium hydroxide. I still can not find it. Do I need new glasses

It is implied by this statement, although it may also relate to strontium carbonate.:

"Relative to calcium, strontium was nearly unchanged in the limewater compared to the solid quicklime. The slight elevation in the limewater is above the background noise, however, since the emission signal from strontium is so strong. The reason for this slight elevation is that strontium is even less likely than calcium to precipitate onto the bottom of the limewater reservoir, and so stays more in solution than calcium."


This reference (below) says the solubility is 0.061 molar for strontium hydroxide, and since calcium hydroxide solubility is 0.0204 molar, it would seen strontium hydroxide is a bit more soluble.

Determination of activity product of strontium hydroxide by polarographic method. Kovalenko, P. N. Fiz.-Khim. Metody Analiza i Kontrolya Proizvodstva. (Rostov-on-Don: Rostovsk. Univ.) Sb. (1961), 80-5. From: Ref. Zh., Khim. 1962, Abstr. No. 9B555.

Abstract

The value of the activity product (La) of Sr(OH)2 was detd. on a polarograph M-7-2000 at 20°. The supporting electrolyte was 0.1N LiCl soln. The Sr(OH)2 soly. was min. at pH 12.9. The value of La was 9 ´ 10-4, and Sr(OH)2 soly. was 6.08 ´ 10-2 mole/l.


In reality, it is not simple to compare the solubility of strontium hydroxide to calcium hydroxide, since it depends a bit on pH:

Comparative study of the precipitation of calcium and strontium. Zhukova, L. A.; Chikov, V. S. USSR. Doklady TSKhA (1972), No. 188 235-9.

Abstract

The pH effect on the Ca or Sr content in ppts. from nitrate solns. contg. NaOH, Na2SiO3, or Na2CO3 at const. ionic strength 0.5 (NaNO3) was studied; pH was adjusted by adding variable amounts of NaOH or HNO3. Addn. of NaOH alone caused pptn. of Ca2+ to begin at pH 11.3, and pptn. of Sr2+, at pH 10.8, but at pH 10.8-12.8, the concn. of ca2+ in soln. was higher than that of Sr2+, i.e. the soly. of Ca(OH)2 was greater than that of Sr(OH)2. Above pH 12.8, the soly. of Ca(OH)2 was lower than that of Sr(OH)2. Addn. of Na2SiO3 caused pptn. of Ca2+ and Sr2+ to begin at pH 5.5 and 6, resp. In all cases, stoichiometric CaSiO3 pptd., and no Ca(OH)2 was obsd. at pH ³11.6. Addn. of Na2CO3 caused pptn. of Ca2+ and Sr2+ to begin at pH 5.5 and 8.4, resp.; the soly. of CaCO3 exceeded that of SrCO3 at all pH.
 
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Randy Holmes-Farley

Reef Chemist
Premium Member
Yep. I make up those obscure Russian language articles to fit my opinion because I know that no one will ever check them. :lol:
 

Boomer

Bomb Technician (EOD)
Premium Member
Keep an eye on him Boomer, he's a sly one


Billy more than you think> I have this slick browser and all I have to due is type in a "word", like Strontium, Sr or even str in a box and it will highlight ever "word" on the page ;) So I typed in Sr, Strontium, hyroxide and even stuff like Sr(OH), OH and NOT'A :lol:
 
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