brown stains along rim of pool, vitamin c does not remove stain, idea?

[waterbear]

Good advice as usual from Mbar (Marie)! You can test to see if the staining is organic by putting a trichlor tab in a sock and holding it against a stain for about 15 minues then scrubbing with a stainless steel brush. If the stain lightens, it is organic and chlorine will remove it, eventually. You can try overfilling the pool so the stains are submerged and supershocking to about 30 ppm to try and bleach them out. If trichlor doesn't have any effect on the stains or makes them darker then they are metals. If vitamen C doesn't lift them there are ways to remove them but they can be lenghty and complicated.
A second thing to try is to put some pH down (sodium bisulfate) in a sock and hold it on the stain for about 10 minutes. If this lightens the stain then an acid wash will remove them. If not then you need to call in the 'big guns'. At this point I would suggest getting a Jack's Magic stain test kit and seeing if one of their solutions will help. Be warned that some of their stain treatments can take weeks to complete and can be expensive.

Also ProTeam makes a sequesterant called Metal Magic that is also able to remove some types of metal stains. It is less expensive than the Jack's Magic products and they have a simple test you can do to see if it will work that only involves a bottle of their product, a sponge, and a plastic bottle. Here is a link to it
http://www.proteampoolcare.com/prod_...SpongeTest.pdf
It is not as effective as the Jack's Magic products on some kinds of metal stains but is much less expensive and easier to do so you might want to try this first. It will also tell you if the stain is metal or organic. If their sponge test removes the stain then the product should work if you dose it accoring to their directions in the sponge test link.

It is possible that the staining you have is from scale deposit (calcium). The Metal magic might be effective on this (since it will also sequester calcium, which IS a metal) but if it isn't then acid washing or spot application of acid and a pumice stone (and a lot of elbow grease) will help remove them. If the dry acid has an effect on the stains there is a good chance that they are scale deposits.