Recovery after iron stain removal

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GBDove

GBDove

0
Feb 18, 2018
12
Bolivia, NC
I'm new to TFP, but have been treating my pool for several years. I had a yellow stain on my pool walls, which I identified as iron using ascorbic acid. I decided to treat it with Stain Free (Citric Acid).It required pool chemistry as follows: pH 7.2-7.6, TA 80-120 PPM, CH 200-400 PPM, CYA below 50 PPM, phosphates < 100 PPB, FC =< 1 ppm. I brought my pool chemistry to these requirements and added the Stain Free and turned off the pump for the evening. The stains were gone by morning, and I added Metal free and vacuumed the pool and backwashed as prescribed. I added Polyquat 60 to protect against algae. I also have a CuLator pouch in my skimmer basket. I am trying to bring the FC back up to 1 to 3 ppm, but have added a gallon of Clorox with no effect. The following chemistry was recorded most recently: FC-0.5ppm, pH-7.2, Temp.-82 deg. F, TA-60ppm, CH-275 ppm, CYA-90, CC-0 ppm. The label says not to shock the pool for a week. I am concerned that the low FC will invite algae back into the pool. Should I sit back an relax for a few more days before shocking the pool, and if so, what should I use to shock it?
 
You definitely need chlorine in there. Just don't go to shock level. Shock level for your pool with CYA at 90 would be 35 PPM. If that Stain Free is similar to ascorbic acid, it will probably take a decent amount of chlorine before the FC starts to hold. Try putting in 8 to 10 PPM of FC and check it a couple of times a day. It will disappear rather quickly while it neutralizes the citric acid in the pool. Just keep topping it back up. Eventually it will start to hold and then you can go back to normal chlorination. Be sure to turn off your SWG while you do this and use only liquid chlorine to increase your FC level. SWG's are not meant to bring the FC level up from a low number. They are slow and steady and ideally just replace what you lose daily.
 
Use pool math at the top of the page. Enter your gallons at the top left and put in 0 in the left column and 8 in the right column. Put 10% as your chlorine source and it should tell you to add 100 oz. That will get you an increase of 8 PPM.
 
I have added 4 Gallons of 6% Chlorine to the pool. The latest was this evening. I check the FC each morning and it has been zero when I added the chlorine. That seems to be a lot of chlorine. Before added this last gallon, I backwashed the filter. Something appears to be eating the chlorine. I expected the rate of decrease of the FC to be less by now. Is there any thing else I should be doing?

Thanks for your counsel,
 
The FC seem to have stabilized at 3 ppm, however the water, though clear, is aqua not blue. The chemistry is as follows: pH 7.6, temperature 82 deg F, TA 100, CH 250, CYA 100. The color seems to indicate some yellow influence in solution. The walls and floor are not stained. The water is otherwise clear. I added bleach to raise the FC to 7 ppm.
 
Today I backwashed and refilled the pool. From the tips section on the website, I put on polarized sunglasses to view the pool. I could easily see a ring of yellow stain when the pool level was dropped. My CuLator pouch was yellow indicating iron bound in the pouch. I identified the stain as inorganic using a lemon. I must not have done the stain removal correctly. I will try again.
 
Try keeping the pH on the lower end of the scale (7.2 - 7.4). Higher pH can cause the metals to fall out of solution in the water. Also, you might just try adding more of the metal sequesterant first by itself and see if that does the trick. Avoid the citric acid if you can. If your CU Lator bag turned yellow, you must have a decent level of metal in your water.

One other option you could try is to drain your pool and refill it once you're happy with the stain removal. That will take out the metals from your pool, and even if there is some in your refill water, it will most definitely be a smaller concentration than it is now. With your pool only being 10,000 gallons, it shouldn't cost you too much.
 
I added Metal free to the pool, and it seemed to remove the stain, but the pool is still aqua. I am not clear on what is a sequestrant, since the label don't explicitly say what it is. Is Metal free a sequestrant or is the CuLator? or both? Once the metal is sequestered, should I backwash to remove it from the system? Do I need to brush the floor and walls to get the molecules suspended and removed from the pool by filtration? This all started after I had a clear blue pool, and a heavy rain filled up the pool and turned it green. Is the green a suspension or something in solution? Since the green hasn't been removed by the sand filter, I am reasoning that the sand is too coarse, or the green is in solution. When I put in the Stain Free, I missed the part about the pulp based filter aid, and since then I have been looking for such a product, but haven't had any luck finding a product that meets that definition. Can you suggest a place I might look?
 

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The CULator is not a sequesterant, it just catches the metal ions in the water so they don't return to the pool. I used one myself, but I'm not really sure if it did anything. I placed it in my pump basket to do its thing, but it never really turned any type of color. Reviews have been kind of mixed on it.

I believe the Metal Free is a sequesterant, although I have no experience with it. Since all your stains are gone but the water has an aqua tint, that would lead me to believe that you have a high concentration of metals in the water. They've just been lifted off the walls and floor and are now in solution.

If it were me, with the pool only being 10K gallons, I think I would just drain it and refill with fresh water to lower that concentration down. I'm not sure if you can drain a fiberglass pool completely, but even an 80 to 90% drain and refill will lower that iron concentration quite a bit. Now, this applies as long as your not on well water. If you're on a well, you may want to rethink things because your well may have iron in it.
 
DeanP66 said:
The CULator is not a sequesterant, it just catches the metal ions in the water so they don't return to the pool. I used one myself, but I'm not really sure if it did anything. I placed it in my pump basket to do its thing, but it never really turned any type of color. Reviews have been kind of mixed on it.

I believe the Metal Free is a sequesterant, although I have no experience with it. Since all your stains are gone but the water has an aqua tint, that would lead me to believe that you have a high concentration of metals in the water. They've just been lifted off the walls and floor and are now in solution.

If it were me, with the pool only being 10K gallons, I think I would just drain it and refill with fresh water to lower that concentration down. I'm not sure if you can drain a fiberglass pool completely, but even an 80 to 90% drain and refill will lower that iron concentration quite a bit. Now, this applies as long as your not on well water. If you're on a well, you may want to rethink things because your well may have iron in it.
Click to expand...

Talking with the company that installed the pool, they said that draining the pool below the skimmer opening brings the possibility of rupture of the fiberglass walls. I don't want to chance that.

I reapplied the stain removal process using Natural Chemistry's Stain Free (Citric Acid), including putting Fiber Clear, a cellulose filtration media, on my sand filter. I lowered the chlorine level to 0 to 1 ppm and kept it there for the duration of the treatment process. I added Metalfree as prescribed and kept the chlorine between 0 and 1 for a week. The pool clouded up and became greener than before. After a week I started a slam, which took 6 days and twenty to thirty gallons of bleach. The end point of the slam was reached as described in the TFP slam process. I stopped adding bleach and started the downward drift of the chlorine from 24. This is the end of the first day. The chlorine read 22 this morning. The water color is almost a sky blue, and the chlorine smell was evident. It rained overnight about 1.5 inches. My wife said the stain was back. I checked the validity of the sighting with a vitamin C tablet. The cost of the bleach was higher than I expected, but less than the chemicals. I thought the blue color of the pool meant that the metals had been removed, but not so. Where is the metal hiding? The CULator pouch in the pump basket has a small patch of green on it, indicating nickel, but no copper or iron. The metals should have plated on the walls and floor from the slamming process, so my check of copper and iron, which indicated none of either, was fruitless. I am very disheartened. Question: Since the bleach that I used to slam the pool was only 6% Chlorine and 94% other, did I add 'other' ingredients to the pool during the slam process? Help! My hair is already too thin!
 
I don't think the bleach had anything to do with it. The 94% "other" is mostly water and salt I believe. Your problem may be doing a SLAM right after a stain treatment. You're not supposed to do one for at least a couple of weeks. The high chlorine concentration can bring the stains out of solution and back onto your walls and floor. The other rule is to keep your pH on the low end (7.2-7.4) to keep your stains from returning.

Since it seems you apparently can't drain much water in your fiberglass pool, your best option is to sequester the metals by lifting the stains and using sequesterant to keep the metals in solution. The sequesterant gets broken down over time by chlorine so you have to add a monthly maintenance dose to keep it in the pool. I have no experience with the Metalfree you used. I have only used Metal Magic with excellent results. There was even a guy on here that had recurring stains while he was using Jacks Magic (purple, blue, pink) sequesterant who switched to Metal Magic and just added it by itself without any AA or citric acid and it removed the recurring stains and kept them away for much longer. He was adding over a bottle a week with the Jack's Magic and once he switched to Metal Magic, his maintenance dose was only once a month.

If I were you, I would try putting in 1.5 to 2 bottles of Metal Magic and see if that lifts the stains once again. It should, because they are fresh, having just fallen out of solution and back onto the floor and walls. If they get lifted back into solution, just add a maintenance dose every month or every couple of weeks if you're worried about them coming back. I use half a bottle every month in my 20,000 gallon plaster pool, so I would bet that your pool would be fine with that same amount if not even less.

When doing the AA or citric acid treatment, the one thing you want to avoid is getting algae because of the fact that you can't use shock levels of chlorine after a treatment. It just puts you back to square one. So, if you were to do another treatment with either AA or citric acid, you should start bringing your FC up no more than an hour or two after you add the sequesterant. There's no good reason to wait. You're just giving the algae more time to get a stranglehold.

Here's a good place to get the Metal Magic and if you buy at least 3 bottles at a time, the shipping is free.

https://sunplay.com/products/proteam-metal-magic-32-oz?variant=6881712603171&gclid=CjwKCAjwp7baBRBIEiwAPtjwxN_te0m8KrScr-PHmHxuGAp146IrBquMnQUV2gomO_VMrAR0tyQvdhoC3pEQAvD_BwE
 
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