Metals Stains

[Butterfly]

When would be the best time to do a metals stain treatment?

1. before/after close or before/after open? or does it matter? (I was just thinking that the water temp will soon be cold enough to stop chems - 76 now)
2. If the plaster is only 7 mos. old (& the stains are younger than that) , would the sequestering agent do it alone? (w/o the ascorbic acid treatment?)

Also, is it possible that the staining can be caused by the new light fixture? It has some kind of metal cover and in the deep end where the staining is. Pool store found no iron in fill water.

Marie, we did the vitamin C, and yea, it is metals.

Joyce

 

[mbar]

If you are going to close the pool soon, I would wait till you open in the spring to do the stain treatment. I wouldn't go through the expense and time it would take to do it now. I have closed my pool with stains in the past, and when I opened in the spring the stains were gone You can put in some sequestering agent now if you want to - It may lift the stain especially if you take the ph down to 7.2 for a couple of days. Just make sure you get the ph back up before you close, because I know mine usually gets low over the winter. It will be good to have some sequesterant in the water over the winter too. I would be surprised if the light fixture is what has caused the stains - they are ususally made of aluminum or plastic, but you can check the screws, sometimes they are not the right kind and wil rust. There are so many ways to get some metals in the water, it is hard to know exactly where they are coming from. In any event, it won't hurt to leave the stains - if they don't dissappear over the winter, you will be able to get rid of them in the spring. Feel free to ask any other questions you may have.

 

[Butterfly]

Thanks Marie. Will put in some sequestering agent and hope that they are gone in the spring!

Joyce

 

[gtm]

I’ve resurrected this thread only because I’m not sure where else to put it. If one of the moderators wants to move it to somewhere more appropriate, that would be great.

I’ve been having stain problems for awhile. The bottom of the pool is generally grey. I’ve read everything here (and on the Pool Forum) that I could find about stains, and the Vitamin C test was my first try since everything I read seemed to be consistent with metal stains. I tried and tried and tried, but the Vitamin C application never made any difference at all.

I was in the GNC store the night before last and noticed that my usual bottle of Vitamin C said that the active ingredient was “calcium ascorbate” in a “time release” formula, while another bottle said “ascorbic acid” was the only ingredient.

I bought a bottle of the latter, put a half dozen caplets on the bottom in the shallow end of the pool, and it’s really rather amazing. My pool now looks like a grey skunk. It’s still mostly grey, but with a brilliant white stripe running down the middle where the Vitamin C ran down the slope.

I’m sure the pros are laughing at me now, but I thought that Vitamin C was Vitamin C. I only post this in case someone else with metal stains might also need to know to read the label on the Vitamin C bottle!

Cheers, Gary

P.S. Can’t wait to do the full treatment!!!

 

[Guest]

Vitamin C is ascorbic acid. Calcium ascorbate is the calcium salt of ascorbic acid. Technically, it is NOT vitamin C but rather a precursor.

 

[chem geek]

Ascorbic Acid can be thought of as "hydrogen ascorbate" in the sense that "calcium ascorbate" is the same except that the hydrogen associated with the acidity is replaced with a calcium so it's a salt of the acid. This means that calcium ascorbate is not a weak acid, but a weak base. Though it will still have the reduction capability that you want to reduce iron, it will not be acidic which is something you also want to lower the pH to keep the metal iron ion more likely to remain in solution. Technically, you could lower the pool's pH with acid first and then use calcium ascorbate, but that seems like a lot of trouble when ascorbic acid will do what you want directly.

I recently bought 2 pounds of ascorbic acid here and it seemed to be a good source. It didn't work well in my pool to remove some iron stains, but that's probably because they are very old -- probably around 5 years old now. I used the ascorbic acid in bulk in the pool, but I may try a direct application over a single stain using a jar to see if that makes any difference.

Richard

 

[gtm]

For others who might be reading, I just wanted to reiterate that the ascorbic acid and calcium ascorbate were both labeled "Vitamin C" on the front. I got fooled for a long time and my main reason for posting was the hope that it might save someone else from making the same silly mistake.

That said, I enjoyed the chemistry lesson. All the stuff I heard at GNC about "easier on the stomach" and such makes more sense now. Always fun to learn something new!

Finally, to Richard, thanks for the update on your "old" stains. I saw your post about that back in November to the thread describing how to do the treatment. My stains are somewhat old as well, but only 2-3 years, so I was curious what your experience would be. Hopefully mine will go better.

Thanks guys!