Vinyl liner stain

[shircri]

This is the second year for our AquaRite salt water generator for a 30,000 gallon in ground pool. I didn't notice it last year, but this year, there is visible yellow staining of the vinyl liner where we add the salt. We are using Diamond Coarse Solar Salt and it dissolves very quickly. Has anyone had this experience and have a theory/solution? Our chemicals check out fine.

[waste]

Where do you get the salt? I ask because I've heard that the 'big box' stores' pool salt often contains yellow purucite (sp) even though it's labeled as pure I don't know if this is what's going on in your case, but thought I'd mention it.

[shircri]

We have been getting the salt at Home Depot in 40 lb bags. It is identified as water softener salt and is labeled as pure salt but apparenty that is not the case! We now know to sweep to dissolve the salt more quickly but don't know how to deal with the stain already there. I found a previous post (through Google) by waterbear identifying the stain as iron. It also talked about adding "sequestrant" but I do not know what "sequestrant" is!

[mbar]

Sequestering is to get any metals that are in solution to get bound up so that it won't fall out and stain the surface of the pool. It can sometimes lift new stains off the pool surface by adding the sequestering agent and lowing the ph to 7.0 - 7.2. A sequestering agent is anything that says it "removes" or controls metals . Let us know how you do - if it doesn't work, you can add some ascorbic acid (vitamin C) to lift the stains, and then the sequestering agent to bind with them so that the metals are contained in solution.

[shircri]

Thank you so much. This afternoon I crushed some Vitamin C and let it drift down on the stain and just watched as the stain disappeared! It covered about a 4'x4' area of the vinyl of a 30,000 gallon pool. Do you think it is necessary for me to add the metal out now or do you think it will just filter out on its own?

[mbar]

Metals don't filter out That is why the sequestering agent is needed. It may be ok for a while, but as soon as you get your chlorine high, and your ph is over 7.6, you will see the stain start to form again. I would add the sequestering agent to be on the safe side.