I can tell you what I did to prevent the Iron staining. We are on a very hard water iron/magnesium rich south Texas well.

I initially filled our pool from the water softener where I had installed a 2 micron whole house filter. While the pool was filling I added the prescibed amount of metal out and polyquat. These two products seem to work great together to allow your filter system to remove metals. Since I was going to be using an SWG I didn't mind the added sodium in the water. It took a lot of regeneration cycles and several bags of salt to fill our 26K gallon pool.

I'm using a 26" sand filter with Zeolite as the filter medium. I allowed the filter system 2-3 days to filter the water before turning on the SWG.

By day 4 the SWG was switched on and has been maintaining 3PPM FC ever since. Water is crystal clear with no staining.

Since I now have my salt levels where I want them I fill directly from the well with the same 2 micron whole house filter attached to the end of the hose. It seems to be working as I have not seen any signs of staining. I do watch the PH and TA levels and keep them in check with Muriatic Acid.