Acid wash or re-surface

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The color of metal stains depends on the compounds formed.

The oxidation states of the metal ions affect which compounds can form.

Vitamin C changes the oxidation state of metal ions by donating electrons and this reduces the oxidation state.

Copper can change from copper II to copper I.

Copper(II) oxide or cupric oxide is a compound with the formula CuO.

It is a black solid, it is one of the two stable oxides of copper, the other being Cu2O or copper(I) oxide (cuprous oxide).

 
This might be the reaction of aluminum sulfate and the copper (II) Oxide.

Al2(SO4)3 + 3CuO --> Al2O3 + 3CuSO4

Aluminum sulfate + Copper (II) oxide --> Aluminum oxide + Copper sulfate.

Aluminum oxide is usually white, so, if the copper oxide is becoming aluminum oxide, it might be a white stain, which will be ok for a white pool but it might be bad for a darker color plaster.

Darker plaster usually hides copper stains as long as the stains match the plaster color.

Some plaster is a turquoise, blue or green and that hides turquoise copper stains.

Darker grey or black plaster can hide grey or black copper stains.

Using aluminum sulfate on dark plaster might leave a white stain that looks worse than the darker stain.
 
Sulfamic acid forms a compound called Copper(II) Sulfamate, which is a relatively stable compound.

Molecular Formula: CuH4N2O6S2.

Molecular Formula: Cu(NH2SO3)2.

CuO + 2NH2SO3- + H2O --> Cu(NH2SO3)2 + 2OH-

Copper Oxide + sulfamate ion + water --> Copper sulfamate + hydroxide.

CuO + 2NH2SO3H --> Cu(NH2SO3)2 + H2O

Copper Oxide + sulfamic acid --> Copper sulfamate + water.

Note: Sulfamic Acid is a strong acid (pKa =1.0) and completely dissociates in an aqueous solution.



Copper Sulfamate.gif

The sulfamic acid also forms chlorosulfamate and dichlorosulfamate, which locks the chlorine up for months, which is one of the reasons that you need to drain and refill after the stains are lifted.

You also need to get rid of the metals that are attached to the sulfamate ions because they will eventually form new stains.

Note: Never drain unless you verify that it is safe to do so.


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OK I know its been a week but I had to get to store to get Vitamin C!
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OK I know its been a week but I had to get to store to get Vitamin C!
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Encouraging. I guess I need to fill pool with C and drain but I know there are lots of details.
 

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OK I know its been a week but I had to get to store to get Vitamin C!
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kimkats said:
I am to watch and thank all that have given their input on this thread. I can't wait to see what happens when you get your hands on some vit. C. Just make sure it is WHITE vit. Some color them orange and that will do more harm than good.
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They did have a very slight orange tinge almost white and I only used a few
 
JamesW said:

Ascorbic Acid Treatment - Further Reading

www.troublefreepool.com www.troublefreepool.com
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Would prefer not to drain. I am not a veteran DIY pool maintaining person. But I would like to be much more involved because a lot of stuff happened right under my nose (like this stain) and the advice was to acid wash or resurface. But now I see a so much better alternative. So with that being said. I never studied pool chemistry but did study chemistry in school. It seema that I have to bring chlorine down. I will stop my chorinator. What is best novice kit to do pool chemistry analysis or what is simple a good one.
 

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If I get the TF-Pro-Salt does this apply "Becoming a TFP Gold Supporter will get you the most for your donations. For a $100 donation Supporters will get $30 off any item at TfTestKits" And how does one do this?
 
william13 said:
If I get the TF-Pro-Salt does this apply "Becoming a TFP Gold Supporter will get you the most for your donations. For a $100 donation Supporters will get $30 off any item at TfTestKits" And how does one do this?
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Any item including the Pro Salt test kit applies as long as item on the TfTestkits site. Upon your donation you should have received an email with a gift certificate code for TfTestkits. Simply enter that code during your order and $30 will be deducted.

If you cannot find this code drop me a message in private and I’ll get it resent. 👍
 
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Newdude said:
The badge looks good on you. We are entirely volunteer here and every every donation extends the day the lights go out. I really don't want to need to find a new hobby, so THANKS.
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Thank you. I can seriously say the members here are beyond knowlegable, genereous with their time, and patient. This whole thing that my stains are "from iron" and the use of ascorbic acid is amazing. The fact that I probably will not have to acid wash is "Big". Wonder why my pool maintenance person did not point me in this direction! PS I did find the initial welcome letter with the nice perks!
 
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Vitamin C without drainng vs draining pool.
I do understand the difference in protocols
Does one do a much better job than the other?
What are the pluses and minuses ?
BTW My wife asked my pool maintanence person if he did vitamin c treatment and he said "I not just going to throw a bunch of stuff in your pool......you need acid washing" " I do this every week and you need it".
I felt my results with the pills suggested were very compelling! Is my maintenance person trying to dupe me?
 

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