I have a problem with metals. There is 0.25 ppm (I think it's ppm) Cu and Fe in the water, and light brown staining on my gunnite pool. Ascorbic acid rubbed on the stain does nothing, nor does treating the entire pool with ascorbic acid. However, sodium bisulphate in a sock (placed on the stain) takes it away in a flash.

I am assuming that the ascorbic acid is most likely a weaker acid than the sodium bisulphate, and that is why one removed the stain rather than the other. If that is the case, I am also assuming that bringing the pH of my pool down to a certain point and proceeding from there would do the trick. However, I would like to know if anyone has any experience with this. I don't want to drop it too much and ruin my equipment. I can bypass my filter, but unfortunatly, not my heater.

Currently, I am using 4 quarts of Proteam Metal Magic in my ~12,000 gallon pool (on my 6th day), and it is lifting the stains *very* gradually. I'm also hoping it took care of the metals in the water.