Results of Ascorbic Acid Treatment for Stains

[Cookieman]

I have kept the ph low - 7.0 - 7.1 since trying the ascorbic acid treatment the second time. I did try the magic eraser on the steps one time when level got low enough. Some came off, but very difficult. I had an interesting conversation with a technician at JacksMagic. Filled her in on issue and gave her my numbers. When she heard calcium was only 90, she said Jack's products need calcium levels of 200-400 to work best as it gives it something for the metal to bind to. First I had heard of that. She believed that is why even double dosing did not sequester all the metal. I asked her about the sequestering test kit (JimK used one to determine if he had enough HEDP in his pool), but she did not try to sell it to me, but recommeded trying to raise calcium level first. Any thoughts? Any chorine now higher than 3.0 -3.5 makes the staining worse. Just been adding small amounts of AA to keep stains at bay temporarily until I can find out how to make the HEDP work. If the calcium addition sounds reasonable to the forum experts, where is best place to purchase it or brand (if it matters). Will calcium addition affect PH?

[JimK]

I have kept the ph low - 7.0 - 7.1 since trying the ascorbic acid treatment the second time. I did try the magic eraser on the steps one time when level got low enough. Some came off, but very difficult. I had an interesting conversation with a technician at JacksMagic. Filled her in on issue and gave her my numbers. When she heard calcium was only 90, she said Jack's products need calcium levels of 200-400 to work best as it gives it something for the metal to bind to. First I had heard of that. She believed that is why even double dosing did not sequester all the metal. I asked her about the sequestering test kit (JimK used one to determine if he had enough HEDP in his pool), but she did not try to sell it to me, but recommeded trying to raise calcium level first. Any thoughts? Any chorine now higher than 3.0 -3.5 makes the staining worse. Just been adding small amounts of AA to keep stains at bay temporarily until I can find out how to make the HEDP work. If the calcium addition sounds reasonable to the forum experts, where is best place to purchase it or brand (if it matters). Will calcium addition affect PH?

Interesting. When I was dealing with my metal staining issues I contacted Jack's Magic a few times and don't remember him asking about my calcium level, which usually checks out at 200-250 (but then again that was several years ago, so I'm not sure).

[mbar]

This is only from my experience, I do not have a chemistry degree. One thing I noticed is when the pool gets milky white after the ascorbic acid treatment the stains don't tend to come back. I think it is when the calcium binds with the HEDP and then it turns the pool milky. It does filter out eventually, which is why I think that the stains don't come back - the metals are filtered out with the mess. I know that I have had to use a lot of ascorbic acid this year, and I never had the milky mess. I also did not have my calcium any higher than 250, so maybe I did not saturate the water enough, and my calcium didn't drop much. Other years my calcium dropped about 150ppms. I don't know which is worse, or more expensive. I usually use a floccing agent when I get the milky water (after about a day). So that is expensive, the calcium is expensive, and the HEDP is expensive. It is your call, but if the stains are only on the steps I would just put some ascorbic acid in a sock and rub it on the steps. I am just wondering if it is only on the steps, or maybe you don't see the stains on the liner. Is your water blue, or does it have a greenish tint to it? I have a white fiberglass pool, and when I have staining it turns the pool yellow, so blue and yellow make green - which gives my water a slight green tint. It isn't very noticeable, but since I am a stain nazi I can pick it out right away.

[PoolDoc]

When she heard calcium was only 90, she said Jack's products need calcium levels of 200-400 to work best as it gives it something for the metal to bind to. First I had heard of that. She believed that is why even double dosing did not sequester all the metal. . . . . Will calcium addition affect PH?

Last first: adding calcium (chloride) will not affect the pH much, if at all.

Regarding the "calcium giving the metal something to bind to" . . . She may be referring to something real, but not as stated. Calcium is ALSO a metal, and you can't bind iron to another metal in pool water. That is, you're not going to form something like ferric calcium.

BUT, I know from my own experience that having calcium carbonate -- marble dust, plaster dust, or cal hypo residue -- DOES collect metal out of the water. Essentially, you end up staining the dust, instead of the pool.

The whole "HEDP needs calcium" to work doesn't make sense to me, and it doesn't really fit with the old Monsanto Dequest manuals I have, but then I don't understand chelation chemistry at any fundamental level. So, again, it's possible she's referring to something real, but with a slightly bogus explanation

One thing I noticed is when the pool gets milky white after the ascorbic acid treatment the stains don't tend to come back. I think it is when the calcium binds with the HEDP and then it turns the pool milky.

That's interesting, Marie, but I have no idea why that would be happening. I'm going to ask Chem_Geek to read through your's and Cookieman's posts and this thread, and see if he has any possible analytical explanation of what might be going on. It's a whole lot easier to make good recommendations, when you understand what's happening. . . and why!

[JimK]

.....BUT, I know from my own experience that having calcium carbonate -- marble dust, plaster dust, or cal hypo residue -- DOES collect metal out of the water. Essentially, you end up staining the dust, instead of the pool.

.....

I wonder if that's where the metal in my pool went (recent bucket test revealed no metals). Up until this season (when I learned here only to shock when needed; ie cloudy, CC present, algae problem) I was "shocking" about every 2 weeks with cal hypo (2# of 68% each time). Each time the water would get cloudy, but clear by morning (I alway shock in the evening). Perhaps this was "grabbing" the metals so they could be filtered out?

[Cookieman]

To answer Marie's question on stains just on steps - the stains show up first (better) on steps because they are white. If left untreated, stains also appear on vinyl, skimmers, and even navigator. How do I raise the calcium hardness without going to pool store? Is it worth a try to get it to maybe 200. Would any of you recommend that before trying more HEDP or just up the amount of HEDP after ascorbic acid. I have been keeping FC low 2.0-3.5, but have started to raise my PH as it has been at 7.0 for nearly a month now trying this treatment. Going to start bucket test tomorrow. Thanks

[Cookieman]

On second thought, probably don't need bucket test at this point since I know meta is in water. Wouldn't bucket test be more appropriate after I treat again with HEDP product?