It may be possible to greatly reduce iron in pool water

chem geek

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chem geek,

How good approximately , if any, would the new formula Natural Chemistry product with Alum versus Aluminum Chloride be at removing iron and other metals, versus the old formula in percentage terms?

Would the baquacil oxidizer being a stabilized hydrogen peroxide solution, and not breaking down as quickly in sunlight, make any difference to the overall method, or results; bearing in mind the HP and AA method recommended above neutralizes the HP before sunrise with large chlorine additions?

A question in regards to Zinc Chloride, I have read that it is used in the galvanization of metals, iron being one of them. Could it be used to the protect the motor, or other metal parts present in the pool? This might be the case if Lanthanum(iii) Chloride Heptahydrate is in someway corrosive to metals. Or would it bind/galvanize, in the presence of HCL acid, with iron to make its removal easier?
I don't know how good or bad the Alum salts would be compared to poly aluminum chloride. All the papers you linked to referred to using PAC, not to using just alum floc.

The Baquacil oxidizer having stabilizers usually means metal chelating agents such as polysulfonic acid since some metals (such as iron, copper, manganese, nickel and chromium) catalyze the breakdown of hydrogen peroxide, but ironically silver improves stability. The solutions are also kept at lower pH which also helps with stability. Acetanilide may be present to reduce the breakdown of hydrogen peroxide in sunlight. The only difference this makes in the method is that it can be done during the day rather than only at night.

Zinc cannot be used in pools because chlorine oxidizes it. Galvanized steel is zinc coated and the zinc helps to protect steel from getting oxidized, but zinc itself is relatively easily oxidized by chlorine. You can put in a zinc paper clip into pool water for a day or two and you'll see what I mean. The lanthanum chloride heptahydrate is not corrosive to metals. Zinc ions in the water won't galvanize anything. They are already oxidized and won't revert to being a metal. Instead, they might form oxides that can stain if the zinc levels get high enough.
 

smallpooldad

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Aug 6, 2008
429
Honolulu
JamesW,

I am not sure if the word dissolve is appropriate, chem geek might describe it differently. But yes a larger amount than usual amount of Hydrogen Peroxide was used and did break up the silicate scale into a large sandy mess which was filtered out, backwashed out, and vacuumed out of the pool. In fact there was a fairly large sandy beach at the bottom of the pool.

I think that the high oxidation potential of HP might have had something to do with the breakup of silicate scale. Whether or not it is dissolved as well I cannot tell, as I have no way of measuring dissolved silica in the water before and after the treatment with HP.

Dissolved silica from the water was later removed from the water using Natural Chemistry "PHOSfree Commercial Strength", and is also being controlled weekly with the Acrylic Acid Copolymer chemical, presently supplied by using Jack's Magic Magenta Stuff.

However I did note a fairly large drop in TDS from around 1800 - 1900 to around 1100, if I remember correctly, after all the treatments were done. TDS has rested in the 1180 to 1280 area for the last 5 or so months.
 

smallpooldad

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Aug 6, 2008
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Chem geek,

Thank you for the quick reply.

Well Zinc Chloride remains a mystery.

Will the Baquacil oxidizer which have as you wrote metal chelating agents help to remove existing iron, and other metals during the HP/AA treatment?

I will try and do some research on Alum versus Poly Aluminum Chloride and report back either way.
 

smallpooldad

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Aug 6, 2008
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Honolulu
chem geek,

Below are some links to Alum versus Poly Aluminum Chloride. It seems Alum can be substituted for Poly Aluminum Chloride.

It seems that Alum is slightly less effective than Poly Aluminum Chloride in removing metals and silica but not by a great percentage. If the dose is increased it can compensate for this, but its downside as you probably already know is it creates more sludge, lowers the pH somewhat, leaves somewhat more Aluminum residue, decreases the alkalinity, does not work well in waters with temperatures lower than 68 F, takes longer (more days) to create clear water, and is optimal at a pH of 6.8 to 7.00. This is as I read it, but I could be wrong, so please let us know what you think.

This would increase the cost of usage somewhat as one would have to bring the pH up, and the alkalinity. In a word it is "messy", but it will work nearly as well as Poly Aluminum Chloride which creates little mess, or sludge. It has until recently, as you probably are aware, been the primary coagulant for cleaning municipal water since the early 1900s. Now overtaken in the last 20 years by Poly Aluminum Chloride, and other polys.

http://www.waterhouse-bc.ca/Coagulant%20Changeover.pdf

http://wedc.lboro.ac.uk/resources/conference/20/Malhotra.pdf

http://www.water-chemistry.in/2011/01/instead-alum-use-poly-aluminium-chloride-coagulant-in-water-treatment/

http://www.wioa.org.au/conference_papers/2001/pdf/paper6.pdf

http://www.fwr.org/wsaa/wsaa41.htm

http://www.gewater.com/handbook/ext_treatment/ch_5_clarification.jsp

A guess, Zinc Chloride is fairly acidic in water, perhaps it is being used to lower the pH to help the Alum perform better. Fortunately it is reported that Zinc does filter out well in a sand filter.

https://www.applichem.com/en/shop/product-detail/as/zinkchlorid-fuer-die-molekularbiologie/
 

chem geek

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The amount of metal sequestrants in stabilized hydrogen peroxide are only enough to bind to low ppm amounts of metal in the concentrated hydrogen peroxide solution. The amount added to the very large volume of pool water will be negligible.

As for zinc chloride, it is not very acidic and that link is for very concentrated solution whereas the concentration in the phosphate remover product is far lower. If one wanted to lower the pH, one would just use a small amount of strong acid such as hydrochloric acid or perhaps a phosphate buffer solution for a liquid or sodium bisulfate for a solid.
 

smallpooldad

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Aug 6, 2008
429
Honolulu
chem geek,

Thank you for the reply.

Question:

As Natural Chemistry's "PHOSfree Commercial Strength", new formula is now essentially a slightly stronger Phosphate remover, once the phosphates are gone and then controlled weekly by the Acrylic Acid Copolymer chemical, presently supplied by using Jack's Magic Magenta Stuff, would it not be a lot less expensive, and perhaps even more effective at removing metals, to just dose a small amount of pool grade 100% Alum (Aluminum Sulfate Hydrate), either weekly, every two weeks, once a month, or once a quarter to remove metals?

Alum (Aluminum Sulfate Hydrate), might be bought very inexpensively from a chemical supply house, but I am not sure how fast it degrades or the minimum quantity needed to be purchased.

If the amounts that were added to the pool filter, instead of directly to the pool itself, and were small amounts, say 2.5 oz or 5 oz, it seems to me that the clouding/deposit effect would negligible and short lived so long as regular vacuuming, and backwashing, are routinely performed.

I am led to understand that 4 lbs, in a 10,000 gallon pool, would remove most iron/metals in the water and scale, but leaves a large messy amount to be vacuumed away from the pool's bottom surface, and might take a number of days to remove.

chem geek, What effect would 5 oz and 4 lbs of Alum have on the pool chemistry, and what would be the best way to mitigate those effects if there are any.

This just a thought I had to cut costs and yet still control metals.

Your thoughts on this slightly wacky idea would be welcome.
 

chem geek

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Note that the alum floc is not a metal sequestrant but a flocculant/coagulant. It does not remove iron in a stain but rather removes iron oxides precipitated in the water so that they can get caught into the filter. There are all sorts of high-end clarifiers that would also work to accomplish the same thing so it's a matter of what is most convenient and inexpensive for you to use given that you have so much iron blown into the water. Again, the alum will not remove metal stains -- it will only remove solid particles in the water including iron oxides. In your case, you want to remove silica as well.

Note that DIN 19643 used in some countries in Europe requires coagulation and is usually done with either aluminum or with ferric iron (III). Note that the recommended pH is between 6.5 and 7.2 if aluminum salts are used while it's 6.5 to 7.5 if iron salts are used. Basically, an alum floc works better at lower pH. This is another reason why you might instead consider using a polymeric clarifier if your goal is to remove iron oxides from the water since maintaining a low pH can be more difficult. A metal sequestrant would then only be to prevent staining from any remaining iron including prevention of scale that could incorporate iron.
 

smallpooldad

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Aug 6, 2008
429
Honolulu
chem geek,

The link below may solve the issue as to why Natural Chemistry is now using Zinc Chloride in their new formula for their Extra Strength Phosphate Remover, previously call Commercial Strength Phosphate Remover. It seems that Zinc Chloride mixed with Alum produces Aluminum Chloride.

If this is the case that these two chemicals are now converted to Aluminum Chloride how much better or worse is it when compared to the original formula containing Aluminum Chloride? And what percentage of the solution may now be reconstituted as Aluminum Chloride?

Looking forward to your reply and opinion.

http://wiki.answers.com/Q/Will_aluminium_react_with_zinc_chloride_solution
 

chem geek

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Don't look at something like answers.com. First of all, the aluminum they are talking about in that Q&A is SOLID aluminum. The aluminum in the products you are looking at is already in ionic form so does NOT form solid zinc. Finally, aluminum chloride does not precipitate and both remain as ions.
 

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smallpooldad

Well-known member
Aug 6, 2008
429
Honolulu
chem geek,

My apologies for wasting your time I should have more properly read the chemical notation for aluminum.

However I did find these and they might explain why it is being used:

https://www.lubrizol.com/DispersantsWaterTreatment/TechPapers/Use-of-Zinc-for-Corrosion-Control.pdf

http://www.zincchlorideindia.com/zinc-chloride-uses.html

http://www.prochemtech.com/Literature/Technical/Basic_Cooling_Water_Management_II.pdf

It seems zinc chloride acts as a corrosion inhibitor, it appears when orthophosphates are removed some level of steel protection is also removed, the zinc chloride possibly acts to prevent this. But I will let you be the judge of that possibility.

Additionally this Power Point presentation from Chemtreat mentions the same possibility and interestingly on pages 59 and 60 mentions the following:

Polyphosphates

– Forms calcium polyphosphate films at cathode
– Usually Pyrophosphate or Sodium Hexametaphosphate
• Organic Phosphates (Phosphonate, Phosphinate)
– Forms calcium phosphonate films at cathode
– Most can also serve as scale inhibitors

• Orthophosphate

– Forms calcium phosphate films at cathode
– Potential for iron phosphate deposits
– Potential for calcium phosphate deposits on heat transfer surfaces

And:

Orthophosphate

– Forms iron phosphate film at anode
– Also precipitates with soluble iron

What effects these might have on a pool's surface I am not sure, I thought you might be able to interpret what is stated.

Here is the link:

http://www.chemtreat.com/wp-content/uploads/2012/12/2b-Cooling-Water-Fundamentals-part-2.pdf

Thank you for your time.
 

chem geek

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Mar 28, 2007
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That's talking mostly about piping with chlorinated water -- water that does not have CYA in it to moderate chlorine's strength. Municipal water supplies often add a corrosion inhibitor, usually orthophosphate but sometimes zinc ions can be used.

It's possible that they added zinc to substitute some corrosion control since they would be removing phosphate, but that's a bit strange since one can have a pool with little phosphates in it to begin with and not have any zinc either. Nevertheless, you might be on to something that perhaps they didn't want to be accused of increasing corrosion rates by lowering phosphate levels. Anyway, it doesn't matter to us since corrosion rates are low for other reasons including not having a low pH and moderating chlorine's strength with CYA.
 

smallpooldad

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Aug 6, 2008
429
Honolulu
chem geek,

Thank you for the reply, well that seems to settle why they possibly use zinc chloride.

One quick question, for those of us who have high silica in our water over 50 ppm, such as the island of Oahu, the Central Valley of California, and many parts of Texas, would there be any benefit at all in keeping the "% HOCL" at a high a number as possible to further control silica? Or might it just be beneficial for iron control? Or both?

I am not sure either way that is why I ask the question, please accept my apologies if this is a stupid question but I simply do not know.

Thank you.
 

chem geek

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I don't think the active chlorine level will make much of a difference in either the silica or iron control. Chlorine reacts quickly to oxidize ferrous iron to ferric iron even at low active chlorine levels.
 

Swampwoman

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I somehow missed this thread last year...likely because it was winter :) I'm going to need to read it a few more times to absorb it, but in my possible ignorance, have a question:

Since commercial phosfree has now changed its formulation, would its phosfloc product, which has aluminum sulphide as its main component, possible be a vehicle to "floc out" iron even if its in suspension via metal magic?

I just got a Lamotte iron test and even though I have no staining at the moment, after metal magic treatment, it does read 1 ppm iron. That's less than last year (so maybe the hydrogen peroxide did remove some ;))

Apart from expense and having to vacuum to waste, no real harm theoretically of reducing the phosphate level if there's a chance it might reduce either the historic faint corner stain area that neither AA nor HP nor Metal Magic treatments seem to remove or more importantly, reduce the overall iron load. (Phosphates in excess of 2500 ppb...can't get an exact read. Not really worries about the algae food angle as I stay well-chlorinated...but mildly suspicious of possible historic phosphate scale with embedded iron from the foreclosed years of neglect)

Thoughts?
 
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