Not sure where you are with the pool, but a couple of quick comments:

1. GREEN cloudy water is algae. ORANGE cloudy water is oxidized iron. GREEN clear water is dissolved iron. BUT . . . you can have green clear water (iron) with algae and all you will see is green CLOUDY water.

2. It's possible to have dissolved iron with FC=3 and pH=8, but not likely. It can only happen if the iron is bound with VERY strong chelation.

3. With a sand filter, you should NOT backwash unless you see at least a 3 - 5 psi increase in pressure, over the 'clean' pressure. When you are trying to filter fine particles, you may need to allow pressure to reach 10 psi more.

4. I'm a little suspicious of your filter sand. Quite a bit of sub-spec sand is placed in sand filters. If it's not too hard, I'd recommend buying a bag of LABELED filter sand from a pool store (not: Lowes or Home Depot). Then open your filter, and extract a cup of sand. Let it dry, and then spread several tablespoons of the real filter sand and the sand from your filter on a dark smooth cloth, and compare.