Using iron out

I used the manual filtration method for removing iron from my pool. However, now I have stains around water line. My water is still light green, and came to the conclusion that between the blue liner and yellowing from iron while filtering it is making the water appear green. When I fill a glass with water it is crystal clear. My question is if I can use like a half cup of iron out through my skimmer to circulate through pool then brush to get stains off? I have a pool that is almost 15,000 gallons so a half cup should not affect the water, right?

You don't want to do that.

Iron Out will -- if you add enough of it AND lower the pH -- dissolve iron stains back into your pool water. But, it won't remove the iron from your pool water. AND, it's completely incompatible with chlorine, to the point that, if you have free chlorine, you have no Iron Out left AND if you have any Iron Out, you have no free chlorine!

Right now . . . you need to lower your pH.

Also, since this is basically a continuation of your other thread, I'm going to merge it back into that thread, once I get a chance.