Using Hydrogen Peroxide for Removing Metal Stains

[chem geek]

In a recent thread on another forum, the discussion came up about using hydrogen peroxide to remove metal stains. At first I didn't think this would work, but then realized that hydrogen peroxide is both an oxidizer AND a reducing agent. So using it in place of ascorbic acid is viable. It's also a LOT less expensive. As I calculated in a post in that thread, hydrogen peroxide at $18 for one gallon of 27.5% (in BioGuard® SoftSwim® C) is far less expensive than ascorbic acid at $8-9 per pound. One pound of ascorbic acid reduces 4.8 ppm FC in 10,000 gallons while one gallon of 27.5% hydrogen peroxide (1.12 g/ml density so 1.166 kg hydrogen peroxide) reduces 64.2 ppm FC in 10,000 gallons. So the hydrogen peroxide is 28 cents per ppm FC in 10,000 gallons while ascorbic acid is $1.67.

The reducing power vs. chlorine gives the capacity, but not necessarily the effectiveness against metal stains. Nevertheless, it worked very well for one user and is probably something that people could try here on a selective experimental basis to see if it works against new stains and old stains. If it does, then it's far less expensive than ascorbic acid and it produces no disinfection by-products to get rid of it since chlorine reacts with hydrogen peroxide to produce oxygen gas.

HOCl + H₂O₂ ---> H₂O + O₂(g) + H⁺ + Cl^-
Hypochlorous Acid + Hydrogen Peroxide ---> Water + Chloride Ion + Oxygen Gas + Hydrogen Ion

One difference in the ascorbic acid treatment vs. hydrogen peroxide is that ascorbic acid is acidic while hydrogen peroxide is not so if one uses hydrogen peroxide then one needs to use regular acid to lower the pH for the treatment. With ascorbic acid one did this as well but didn't need to use as much acid because the ascrobic acid itself was acidic. Also, as noted above, if you use a lot of hydrogen peroxide, then when you add chlorine to get rid of it the pH will drop and will need to be adjusted upward once one starts getting a Free Chlorine (FC) reading.

 

[257WbyMag]

That's interesting. If it works as you say it does, then that's just one more solution to metal stains. Cheaper is better too, especially in this day and age.

 

[waste]

THANK YOU Richard :!: :bowdown:

 

[CaOCl2]

Speaking of H2O2, I think one of Jack Magic's product, "O2 Safe Shock", may be sodium percarbonate, and is used to remove copper stains. Sodium percarbonate and water = lots of H2O2.

 

[JasonLion]

My understanding is that O2 Safe Shock reduces copper stains enough to make them simpler to get off using other techniques, but doesn't remove copper stains on it's own.

 

[chem geek]

As I wrote, this is something we need to have tested -- it's not a certainty. We don't yet know how well this works and if it works for older stains as well as newer stains. This is why this is in The Deep End. I suspect that it may work well for iron stains since they truly need a reducing agent for conversion of ferric oxides into ferrous ions, but it may not work as well for copper stains that require acidic conditions and a metal sequestrant. Note that the substitution of ascorbic acid with hydrogen peroxide still requires the use of a metal sequestrant. The reduced iron still needs to be bound in the water or else it will re-stain when chlorine is added and the pH rises again.

 

[Nick Curley]

I have been using hydrogen peroxide to remove stains in fibreglass pool for a couple of years now and it works well. I allow the FC to drop to zero, lower the pH to 7.2 and add 5 litres per 50 000 litres. I am not sure of the strength of the peroxide, but the stains disappear but the next day, my customers are amazed.

 

[smallpooldad]

Chem Geek,

My neighbours who are old have a very old pool that has Black Algae in many parts where the plaster is laminating off. Would this treatment help at all? They cannot at the present time afford to re-plaster and they are currently in poor health so cannot scrub. I help them out with bi-weekly balancing but I to have not been well for the last year, this is the reason for my question. In other words could this be a quick fix? Somehow I doubt it though.

About three years or four years ago we Ascorbic Acid treated and drained the 20,000 gallon pool, it had not be drained in 16 years, the now white plaster was prior to this a deep mud brown. We also spot treated the black algae with chlorine soaked rags and scrubbed, removing what we thought was most of the black algae. They did install a salt generator but their daily/weekly maintenance was inconsistent which seems to have lead to its reappearance.

Bye and bye, well over a year ago, perhaps longer ago, I broached this subject with a post on Hydrogen Peroxide on this site as to its oxidising stain removal possibilties having read about it on other sites, I was informed very strongly (not by you) that my post which was quickly jumped upon and dismissed as being far too experimental and that for the safety of other members it would be completely removed, which indeed it was, it is not even here in my post log as of today, nor is it cached by Google. As I was not about to "Fight City Hall", and for the safety of others, I let the issue go but not without some displeasure although I thought it could be left in "Agree to Disagree" and was dismayed that an honest question could so quickly be shot down without a full investigation. I am glad to see that you are looking at it again and that the site is now keeping a more open mind on this and other ideas. Certainly a large step forward in the thinking of this great site and forum.

Thank you

 

[JohnT]

.

Bye and bye, well over a year ago, perhaps longer ago, I broached this subject with a post on Hydrogen Peroxide on this site as to its oxidising stain removal possibilties having read about it on other sites, I was informed very strongly (not by you) that my post which was quickly jumped upon and dismissed as being far too experimental and that for the safety of other members it would be completely removed, which indeed it was, it is not even here in my post log as of today, nor is it cached by Google. As I was not about to "Fight City Hall", and for the safety of others, I let the issue go but not without some displeasure although I thought it could be left in "Agree to Disagree" and was dismayed that an honest question could so quickly be shot down without a full investigation. I am glad to see that you are looking at it again and that the site is now keeping a more open mind on this and other ideas. Certainly a large step forward in the thinking of this great site and forum.

Thank you

I think the reason your post was moved previously was the suggestion to use Oxiclean rather than hydrogen peroxide.

 

[chem geek]

I doubt that hydrogen peroxide will help much against algae in general and in particular black algae. Just remember that if you try using it, it reacts with chlorine (neutralizes it) so similar to ascorbic acid you will end up with no chlorine in the pool while you are using it. Pools or spas that use only hydrogen peroxide, mostly found in Australia where that is allowed, have to have the level up at around 50 ppm which is pretty high. Algae might be inhibited at that level, but black algae has a waxy surface that most oxidizers have trouble with. Maybe something like chlorine dioxide might work better in that situation (but isn't practical since it needs to be created on-site such as by combining chlorine with sodium chlorite), but generally we recommend using chlorine along with brushing to expose the interior of the black algae to high chlorine levels.

 

[teapot]

Maybe something like chlorine dioxide might work better in that situation (but isn't practical since it needs to be created on-site such as by combining chlorine with sodium chlorite), but generally we recommend using chlorine along with brushing to expose the interior of the black algae to high chlorine levels.

Dryden Aqua now feature a chlorine dioxide tablet that is primarily used to sanitise spas during a deep clean cycle but several may be used together for a pool.

DryOx Shipping may be an issue.

 

[smallpooldad]

Chem Geek and Teapot,

Thank you for the great information. I will certainly look into DryOx or something similar as the black algae seems to be creating an increased demand on the chlorine and I have to supplement the salt generator with liquid chlorine which based on production should not be the case. I realize that runnning the pump longer would also help but because of the very high cost of electricity in Honolulu my neigbour will not run it longer than 10 hours, I talked him up from 8. When I say I am supplementing by that I mean I am paying for the stuff and sneaking it in. My neighbour while a very good person can be somewhat of an A personality and as he old and is not well it is easier to do it this way than to raise his blood pressure. I would also like to drain the pool and work on them with chlorine soaked rags and wire scrubbing but he will not do that. There are many spots. Oh well life is meant to try us and really other than this he and his wife are very good people and neighbours.

JohnT,

Thank you for your reply and you are correct. I did, if I recollect correctly, talk about Oxiclean which some pool owners had success with. I believe that this product does contain produce Hydorogen Peroxide at around 3% to 5%. I am not sure if however if the other contents are not beneficial that I cannot remember. How did you find this post as I cannot find it, could you let me know?

Regardless it will not serve the purpose I was looking for which is to remove black algae in my neighbours pool, and when doing an iron treatment I will stick with the tried and true AA treatment as it has always worked for me.

Thank you all.

Question: Does anyone know where one can buy something similar to DryOx in the US?

 

[Lershac]

Do you mean to say that you are doing thing to your neighbors pool without permission? Um, wow. Your heart may be in the right place, but that's just wrong!

Careful you might get into trouble that way