Obviously it does not do so alone but, according to page three of this very interesting article, chlorine is the essential other half of the sulfamic acid stain treatment equation: Differentiating stains and determining treatment
According to equation (2) quoted from the article above, FC is consumed to a very useful end during a sulfamic acid treatment (which includes Jack's Stain Solution #2 treatment too) when the chlorine is bound and the chloramine is formed. Most Deep End readers probably already know about the resulting consequences in testing (zero FC results) during and after sulfamic acid treatments. Unlike ascorbic and citric acid treatments, it is further interesting to note that FC must be present (non-zero) for this treatment to even work and it also begs the question:
Why not simply add sulfuric acid to the pool instead of sulfamic acid?
As a note of personal history, I was about to place my online order for the Jack's #2 Copper and Scale Stuff treatment (Jack's is available online for not much more money than Internet sulfamic acid "street prices" and I found Jack's tech support to be excellent when I bought my stain test kit) when I happened across a Craig's List ad for 50 lbs of Univar technical grade 99.8 % sulfamic acid for $25. Wow--what unusually good luck and timing I had! The bag was internally plastic wrapped, sealed, and unopened but several years old so I tested the reagent in the same manner that I had used the Solution #2 in my Jack's Magic stain test kit. The Univar "stuff" worked exactly the same as the Jack's #2 Copper and Scale Stuff and a brand new small sample of sulfamic acid that I had obtained from an online chemical company.
I used 22 lbs from the Univar bag so I have enough of it left for spot treatments and another round of treatment next year, if I need it. I'm now racing against the rapidly developing cold weather here in N. central Idaho. My pool water was 74 degrees 12 days ago when I started. Today it was 69. Jack's recommends 65F minimum for their #2 treatment but, anticipating colder than optimum water temps, I mixed my cocktail a little stronger than the Jack's 17.5 lbs prescription for my pool volume. Of course the reaction doesn't end at 65F, but it's going to slow down all the way to closing this year. At the risk of potentially rapid and severe damage to plumbing if my pump were to fail (N. central Idaho can be pretty cold), I will delay closing as long as possible. Hopefully I'll continue to observe progress and the stains will be gone before it gets really cold outside. Jack's says a #2 treatment can take "several weeks", whatever that means. Several weeks is the entire swimming season here in Idaho!
After 7 days, I thought the stains were dimming. Today is day 12 and I know they are vanishing. Even accounting for the sometimes slightly hazy water, the stains have lightened significantly and I am very hopeful they will vanish--or nearly so. I'm wire brushing about every other day now and that always kicks up a little "dust" but brushing seems to be hastening the stain removal process. Per Jack's guidance, I didn't brush for a week, but after reading the above article, I'll try to continue to brush much more often now. Also, I'll use an acid sand filter cleaner when I'm done, per the article too. I've had good results with ProTeam FIlter Magic in the past and I'm using the ProTeam sand filter Dry Clarifier (a cellulose polymer) that I had on hand. Like the Jack's Filter Fiber Stuff, it's hopefully the sort of polymer that the article says can adsorb metal ions. Regardless, I have Culator 4.0 "eggs" in the pump and skimmer baskets and they are turning noticeably blue--similar to the end of last swim season when, based on the results of the Metal Magic sponge test, I removed my iron stains with Metal Magic. Afterwards, last year's Culator 4.0 eventually turned reddish-brown (they never change color overnight , ya' know). I started to use a Culator FillFast filter for our 4.44 ppm Fe fill water mid-season this year and I haven't seen any more reddish-brown in this year's Culator eggs since. I know a lot of TFP'ers don't believe that the Culator eggs work, but they have always performed and behaved for me exactly as Periodic Products describes them and, compared to perpetual heavy sequestering agent usage, I find them to be reasonably priced too.
I'll update my report later--perhaps next year when the forum starts to buzz again and I have more complete results to report.
Although it is extremely effective at lifting stains, sulfamic acid drastically affects water chemistry, as seen below:
(1) (NH2) HSO3 + H2O → (NH4)HSO4
(2) (NH4) HSO4 + HOCl → NH2Cl + H2SO4 + H2O
In water, sulfamic acid hydrolyzes to ammonium bisulfate (NH4HSO4), which then reacts with free chlorine to form monochloramine, sulfuric acid (H2SO4) and water. It is the generation of sulfuric acid that removes the stain:
H2SO4 + Cu(OH)2 → Cu+2 + SO4-2 + 2H2O
When sulfamic acid is applied, the low pH at the stain surface will react with the hydroxide from the copper hydroxide precipitate to form water, allowing the copper to be re-dissolved into solution.
According to equation (2) quoted from the article above, FC is consumed to a very useful end during a sulfamic acid treatment (which includes Jack's Stain Solution #2 treatment too) when the chlorine is bound and the chloramine is formed. Most Deep End readers probably already know about the resulting consequences in testing (zero FC results) during and after sulfamic acid treatments. Unlike ascorbic and citric acid treatments, it is further interesting to note that FC must be present (non-zero) for this treatment to even work and it also begs the question:
Why not simply add sulfuric acid to the pool instead of sulfamic acid?
As a note of personal history, I was about to place my online order for the Jack's #2 Copper and Scale Stuff treatment (Jack's is available online for not much more money than Internet sulfamic acid "street prices" and I found Jack's tech support to be excellent when I bought my stain test kit) when I happened across a Craig's List ad for 50 lbs of Univar technical grade 99.8 % sulfamic acid for $25. Wow--what unusually good luck and timing I had! The bag was internally plastic wrapped, sealed, and unopened but several years old so I tested the reagent in the same manner that I had used the Solution #2 in my Jack's Magic stain test kit. The Univar "stuff" worked exactly the same as the Jack's #2 Copper and Scale Stuff and a brand new small sample of sulfamic acid that I had obtained from an online chemical company.
I used 22 lbs from the Univar bag so I have enough of it left for spot treatments and another round of treatment next year, if I need it. I'm now racing against the rapidly developing cold weather here in N. central Idaho. My pool water was 74 degrees 12 days ago when I started. Today it was 69. Jack's recommends 65F minimum for their #2 treatment but, anticipating colder than optimum water temps, I mixed my cocktail a little stronger than the Jack's 17.5 lbs prescription for my pool volume. Of course the reaction doesn't end at 65F, but it's going to slow down all the way to closing this year. At the risk of potentially rapid and severe damage to plumbing if my pump were to fail (N. central Idaho can be pretty cold), I will delay closing as long as possible. Hopefully I'll continue to observe progress and the stains will be gone before it gets really cold outside. Jack's says a #2 treatment can take "several weeks", whatever that means. Several weeks is the entire swimming season here in Idaho!
After 7 days, I thought the stains were dimming. Today is day 12 and I know they are vanishing. Even accounting for the sometimes slightly hazy water, the stains have lightened significantly and I am very hopeful they will vanish--or nearly so. I'm wire brushing about every other day now and that always kicks up a little "dust" but brushing seems to be hastening the stain removal process. Per Jack's guidance, I didn't brush for a week, but after reading the above article, I'll try to continue to brush much more often now. Also, I'll use an acid sand filter cleaner when I'm done, per the article too. I've had good results with ProTeam FIlter Magic in the past and I'm using the ProTeam sand filter Dry Clarifier (a cellulose polymer) that I had on hand. Like the Jack's Filter Fiber Stuff, it's hopefully the sort of polymer that the article says can adsorb metal ions. Regardless, I have Culator 4.0 "eggs" in the pump and skimmer baskets and they are turning noticeably blue--similar to the end of last swim season when, based on the results of the Metal Magic sponge test, I removed my iron stains with Metal Magic. Afterwards, last year's Culator 4.0 eventually turned reddish-brown (they never change color overnight , ya' know). I started to use a Culator FillFast filter for our 4.44 ppm Fe fill water mid-season this year and I haven't seen any more reddish-brown in this year's Culator eggs since. I know a lot of TFP'ers don't believe that the Culator eggs work, but they have always performed and behaved for me exactly as Periodic Products describes them and, compared to perpetual heavy sequestering agent usage, I find them to be reasonably priced too.
I'll update my report later--perhaps next year when the forum starts to buzz again and I have more complete results to report.
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