Green Glow.

[PoolDoc]

I hope I didn't scare you, but I texted you from the PoolForum Google Voice number -- you don't want to put Metal Free in. It's just citric acid, which can be used to lift stains, but it's no more chlorine compatible than ascorbic acid (Vit. C) and not as good at lifting stains.

What you are looking for is HEDP -- a phosphonate sequestrant that IS more or less chlorine compatible. The problem is, you do not have to list the ingredients in liquid sequestrants, so you're limited to the ones that do list ingredients or put them in MSDS sheets.

Here are options from Amazon:

Jacks Magic The Pink Stuff 1qt (60% HEDP) @ Amazon
20% KemTek HEDP @ Amazon

Other products you might find locally include:

Haviland Stain & Scale Magic (30% solution?)
Jack's Magic Blue Stuff (20% solution)
Jack's Magic Purple Stuff (20% solution)
Jack's Magic Pink Stuff (60% solution)
ProTeam Metal Magic (30% solution)
RamChem Ram Metal Hold ((60% solution?)

Those are all that I can positively ID as HEDP, at this time.

Many other products are being used, including citric acid, EDTA, sodium hexametaphosphate, and so forth, so you need to be careful NOT to buy products unless you can get your hands on an MSDS that IDs the product as HEDP.