Ckk, vacuum that to waste if you can without kicking it back up.
Also, if you swap that 5 micron filter for a 1 micron filter you will catch more iron
Lastly, since you're in an experimental mode, I should mention that I am presently doing a test with Alum floc and iron. Alum foc (or any floc) is not normally recommended at TFP due to sulphates, unrelability, and the potential to mess up your filter.
But, if you can vacuum to waste and have a unique situation, there are times it might turn out to be useful.
In my experimrpent, I took a 5 gal pail of raw well water with 2 ppm iron. I added 1/2 teaspoon of Leslie's Alum. The orange has flocced to the bottom and it hasn't even been 24 hours yet.
This ratio roughly represents what 12 lbs of Alum (this type only) would do in 10,000 gallons of pool water.
Tuesday, when my refills on iron test come in, I'll be able to report how many ppm were removed this way. I can already see that the water above the floc mass is crystal clear, so I'm optimistic.