Ascorbic acid not removing stains

[falken]

27,000 gallon 18x36 IG pool, vinyl liner, brown stains in the deep end and on the stairs. Both areas responded to a vitamin C tablet.
I added 2.75 pounds of AA and waited about 4 hours, stains looked the same, as I added another .75 pounds (all I had left). The next day the stains were lighter but still there.
I went ahead and added the sequesterent (didn't know if I should have waited or not). It has been 2 more days and the stains are even lighter but still obviously there, you can still see where I rubbed the vitamin c tablet on the stains, its a pretty white there but the rest is still discolored.

Should I keep waiting without adding chlorine? Just to get some more AA, or something else?

 

[frustratedpoolmom]

Did you add Polyquat 60? What is the water temperature?

Edit: I reread the AA article and it does say if the stains are stubborn to add more AA and keep the filter on recirculate.

 

[JasonLion]

You need to use more AA. Also, make sure you have the PH down around 7.0 to 7.2.

If the PH is higher than 7.2, try lowering the PH for a day or two and see what happens.

If the PH was already low, you need to figure out how quickly you can get more AA. If you can get more AA in the next day or two, I would wait to add chlorine. If it is going to take longer to get the AA, I would go ahead and start adding chlorine (very slowly) and then start over when the AA comes.

 

[falken]

The PH is 7.0, the water temp is only 70F.

I actually used Stain Free from Natural Chemisty. It claims to be an ascorbic acid treatment and says "Like Vitamin C for your pool!".
Any experience with this? Perhaps its not pure ascorbic acid...

It has a ton of Poly60 in it... It took me forever to clean it up this year, I wasn't about to let it turn in to algae again!

How much more AA would you suggest to use?

 

[falken]

I should also note it has been stained for several years, getting worse each year.

 

[geekgranny]

I did my AA treatment in the fall when the water was way cool; almost cold. It took it over a week to completely lift the stain from the areas that have scale. I, also, added more aa, but had to purchase it at the Vit store rather than wait.

gg=alice

 

[geekgranny]

I don't remember how much extra I used but I think it was at least a double dose, maybe more.

 

[JasonLion]

Stain Free definitely contains ascorbic acid. They don't say anywhere what the concentration is. I would imagine it is close to 100%, but it could be as low as 50% given the vague labeling.

You probably only need another one or two pounds of AA, but it is impossible to be sure. If the stains have been getting worse for years, it is quite possible that they have a lot of metal in them. The thicker and more widespread the metal stain, the more AA you need.

 

[falken]

I did another 2 lbs of Stain Free (only asorbic acid locally I could find). No luck, and i've spent enough on that stuff!

I've added a total of 12 gallons of 6% bleach (one at a time, adding another when FC tests 0), still haven't gotten FC to hold more than a few hours so I assume there was a lot of ascorbic acid in the pool!

The stains off the stairs are gone, and the light stains in the shallow end are gone. The large stain in the deep end is still present. Do you think I should try again with real pure ascirbic acid off the internet or just keep using metal sequesterent and keep the PH near 7.0-7.2 for awhile and see what happens?

I started with the chlorine because algae was starting to form despite the poly60 (a week of bright sun and hot weather with 0 chlorine now). My Ph is 6.6, should I try and take it up to 7.0 now or hold off awhile longer?

 

[frustratedpoolmom]

I would take it up to 7.0 if you are going to continue treating the stain in the deep end, 7.2 if you aren't. Online is probably your cheapest source for the AA but you have to really shop around for the best price. As for continuing with the treatment, that's kinda a personal preference decision, can you live with the stain for awhile? The warmer it gets the harder it will be to keep the pool algae free. You can also add more PQ60 tho it's expensive and creates its own chlorine demand.