Quote Originally Posted by stma View Post
@Ben: I did add a dose of Natural Chemistry's Metal Free into the water..) (the stains DO disappear with the Vit C powder)
Citric acid is incompatible with chlorine; if you have adequate chlorine in the pool, the citric acid will be destroyed almost instantly. This is also true of ascorbic acid (V. C) but it is a better stain remover than citric acid. However, to use either one, you have to operate with low / no chlorine, which is why we recommend dropping the chlorine and adding polyquat, when lifting (dissolving) metal stains, then adding HEDP (somewhat chlorine stable) to KEEP the metals in the water, THEN rechlorinating.

If you use the *old* Metal Free, it was EDTA based, which would still work for a little while in the presence of chlorine. Natural Chemistry reformulated that product on a no-notice basis.