Ascorbic Acid Treatment

[Steve456]

We have the chemicals to eliminate copper staining in our pool. We have added a poly quant 60 algaecide to the pool. Our current pool chemistry is:

Free Chlorine: 2.0
Combined Chlorine: 0.0
pH: 7.6
Total Alkalinity: 70
Cyanuric Acid: 60
Calcium Hardness 230
Copper .7
Water Condition: Crystal clear
Tests Using TF100 Test Kit and Taylor copper test kit

We have both hydroxyethylidene diphosphonic acid and ascorbic acid. Which should we try first on black copper stains?
What should be the pH of the pool before starting ascorbic acid treatment? 7.2?
Does the TA need to be at a certain level for ascorbic acid treatment?
We have always used chelated copper algaecide. A sequestering agent (also called a chelating agent) sounds similar to the chelated properties of the copper algaecide. Both chelated copper and a sequestering agent are suppose to keep the copper in solution. After we add a sequestering agent are we still at risk for copper staining? It does not seem like chemically anything has changed. Do sequestering agents lose their effectiveness with time?
Are we condemned to adding a sequestering agent for the rest of our lives? (I am sure that is the advice we would get from a pool store.)
When we go on vacation or a malfunction of a SWG could lead to another mustard algae outbreak. If we have a CYA of 80 then shocking with bleach would require 34 ppm; that is difficult and impractical. How should we defeat the next mustard algae outbreak without a copper algaecide?

 

[mbar]

I am sorry but I don't have any personal experience with copper staining. I am not sure if the ascorbic acid would take the black copper stains off. I do know that if you have to use certain treatments for copper and you have a heater you do have to bypass it.

Doing the ascorbic acid treatment will take off most stains. However you will have to use the chelating or sequestering agent to keep the copper in solution. Once it is in the water it is very difficult to get rid of - mostly through the dilution of the pool water. I would not recommend using any copper algaecide. You can get rid of any algae with high levels of chlorine (bleach). You just have to be very diligent and consistent with the chlorine levels - and getting it up to 34ppms, and keeping it there is not that difficult compared to dealing with copper in the water. You do have to continuously add sequestering agent as it loses it's effectiveness by getting eaten up by chlorine, and by dilution. The sequestering agents have maintenance dose directions on the bottle.

As for the ph and alkalinity doing the ascorbic acid treatment, the ascorbic acid will likely lower them both. You will also have trouble keeping the chlorine level in the pool after the treatment until all of the ascorbic acid is gone. You can read the sticky on ascorbic acid treatment, and if you have any other questions feel free to ask

 

[JasonLion]

I would try diphosphonic acid first. Ascorbic acid is unlikely to work with copper stains and sometimes makes them even more difficult to remove. In either case it is best to try a small spot to see if they work, before treating the entire pool.