Here are the directions to use Ascorbic acid to rid your pool of metal stains:
Here is the ascorbic treatment:
Take your chlorine down to 0 and PH down to 7.2, if there is chlorine in the water it won't hurt, it will just eat up the ascorbic acid, so you will need more to get rid of the stains. You can add poyquat 60 per directions on the bottle to avoid getting algae while the chlorine is low.
You will need about a half to one pound of ascorbic acid per 10,000 gal. I like to go lighter on it and see if all the stains lift off before adding more.
Put the filter on circulate.
Use a cup and go around the perimeter of the pool and drop it down the sides as you go.
Let the ascorbic acid circulate for 1/2 hour. You will be amazed how the stain just disappears before your eyes.
If the stain is not all gone, leave the filter in circulate and add more ascorbic acid close to where you still see stain. Leave it in circulate until all of the stain is gone. (add more ascorbic acid if it circulates for 1/2 hour and there is still stain)
When the stain is gone, add enough sequestering agent for the volume of your pool - more is better than not enough.
Put the filter back on filter and leave it on 24/7.
The ascorbic acid will bring your ph down, and sometimes the alkalinity. After 24 hours you can start to rebalance the water. Bring up your ph and alkalinity, - use arm and hammer washing soda first, it will raise both ph and alk. Make sure you test in between, because you don't want your ph to go any higher than 7.2. If your alkalinity is in range, and you still need to raise your ph, use Borax to take it up to no higher than 7.2. You can start to bring up your chlorine. You want to do this slowly. It will take a lot of chlorine - I prefer to use bleach only at this time, and try to take it up to your minimum chlorine for your cya according to the "best guess chart" . As you slowly raise the chlorine, watch for stains starting to form. If you see stains, make sure the ph is no higher than 7.2, and add more sequestering agent. You should see the stain lift in a couple of hours. Do not shock! Do not shock for at least 2 weeks! Make sure you keep your ph low for (7.2) for a week or two - it won't be hard because the ascorbic acid and sequestering agnet will help it stay low. Once your chlorine starts to hold, it means that you have used up the ascorbic acid in the water and it will be easy to rebalance the pool back to your regular parameters.
Here are two important notes: High ph along with high chlorine will precipitate any metals that are not sequestered out of the water and on to the surface of the pool again. If this happens take the ph back down to 7, or 7.2 and add more sequestering agent. This should lift the stain off. You can add polyquat 60 to the water before starting the stain treatment to avoid getting algae while the chlorine is low.
Here are two links to buy ascorbic acid:
http://www.chemistrystore.com/Chemicals ... _Acid.html
Since they have really raised the price on Ascorbic acid I tried Citric acid and it worked.Here is a link to citric acid which is cheaper. You will have to use more, and it takes a little longer but it works
http://www.chemistrystore.com/search.cg ... earch2.y=0