Ok.

Run your pump 24/7.

Go ahead with the polyquat, because that will allow you to keep your chlorine low. If you let your chlorine get high, the iron will tend to come out all at once, and all over the pool. Lower the pH to about 7.0.

What you want to do is get the water clear - with low pH and a metal sequestrant, and then gradually filter it out.

If you chlorinate -- low levels only -- via a tab in the skimmer and then gradually raise pH levels from 7.0 to 7.8 over a week's time, using borax, also added via the skimmer, you'll have a good chance of accomplishing that. By the way, borax is one of the very, very few chemicals that you can safely add in a skimmer that has a tab in it.

Once you get the pH up, you can gradually add more tabs to the skimmer to increase the chlorine level. Once you've got a pH of 7.8 and a chlorine level of 5 ppm . . . your iron will probably be gone -- if your filter is working well.

You can also add DE powder to the skimmer which will both cause the filter to stop up faster AND remove more of the iron.

When you add additional water ALWAYS fill SLOWLY through the skimmer with a tab present and the pump running.

Hope this works for you. Do not hurry -- take 2 weeks to do this.

Ben