leejp, yes shocking espeically with high ph will make metals that are not bound by sequestering agent precipitate out and stain the liner.

haze1956,
Yes, one way to get the metal out of the pool is to put a trichlor puck in the skimmer basket and raise your ph up to 7.8 - this will make metals fall out on the filter, which will then be backwashed out, therefore it will get the metal out of the water - the only thing it could also stain on the pool - that's why I like to use the method of sequestering the metals, but the metals do not get filtered out. I also like to put a puck in the skimmer when I am first bringing my chorine up after a stain treatment to make sure if I don't have enough sequestering agent the stain will hopefully fall out on the filter first. I do not raise my ph when doing this - I keep it at about 7.2.