Re: Newbie - Stain removal via ascorbic acid
Ok.
Most likely, you have iron in your well water. Many people don't realize that water softeners remove iron. If you filled with water that had passed through the softener, the iron would have been removed . . . UNTIL the zeolite in the softener was saturated with iron. With most wells, the water needed to refill with the pool would have saturated your zeolite (not Zeobrite) several times over.
In the past, you may not have had problems because you didn't use enough water to 'break through' your softener. But, once you had to the fill the pool, watch out!
(Of course, if you have never used softened water to fill your pool, you can forget all this, except as a reference for the future.)
One other issue: it's quite an irony, but the most common way to REMOVE stains, acid washing, ends up making pool surfaces much MORE susceptible to staining. Acid washing works by corroding away the top layer of plaster, exposing a new white -- but rough and porous -- surface.
Unfortunately, iron stains that have been in place for awhile don't always come up that easily.
Here's your best bet:
0. Start running your pump 24/7.
1. Carefully lower your pH to 6.4 - 6.8. If your kit only goes to 6.8, carefully lower it to that, and then add a little more acid. Keep it there for several weeks. (In essence, you are doing a very, very mild acid wash, among other things.)
2. Use twice weekly doses of polyquat 60 to allow you to run low levels of chlorine without getting a pool full of algae.
3. Maintain low chlorine levels between 0.5 and 2 ppm.
4. Add 1 1/2 times the maximum dose on Metal Magnet or a similar liquid metal control agent. Be sure to allow for any prior use in the past 2 weeks: deduct that from what you add.
5. Brush the pool a lot, especially starting a day after you get the chems in line.
If you're lucky, this will remove the stains gradually. If they do, remember that you are NOT done. You will have moved the iron OFF your pool walls, but BACK into your pool water. You've still got get the iron OUT of your pool, and ONTO your filter.
Chlorinate by putting trichlor tabs in the skimmer. Doing so will help lower the pH and will tend to bring the iron out on the filter. Backwash as needed. If the backwash is orange-brown from the iron, you are making progress.
After two weeks, you're pretty much done: if the iron is not off by then, you'll have to think about replastering, painting, acid washing again, or just living with it.
You can also remove the iron by concentrated application of "Iron Out" which is available from the company in 50# pails. This requires a drained pool, too. BTW, do NOT use Iron Out if you have asthma, and DO have someone around to 'rescue' you if there's a problem. Sodium hydrosulfite (present in Iron Out) fumes can trigger SEVERE acute asthmatic attacks.
Regardless, start bringing your pH up SLOWLY, using borax. Once you get up to 7.6 or so, remove ALL trichlor from your system. (Really! Make sure that there is absolutely NONE anywhere in your pool, pipes or feeder!) Then begin chlorinating using calcium hypochlorite granular chlorine, added DIRECTLY to the skimmer in small doses. Buy some from Leslie's if you need to do so.
Gradually raise the chlorine to around 20 ppm (given your CYA of 100+) and hold it there for at least a week.
Once you've done so, all or most of the iron in your pool water will be gone. And, you'll have removed stains you're likely to remove without draining.
Good luck,
Ben
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Originally Posted by PoolDoc
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