There is a nice and simple ...

There is a nice and simple way to do this that works very well and will get you well blow the 1.5ppm Fe.  Inject on over caustic bleach such that you have a 0.1ppm total chlorine but you must also have the pH over 8.0. It is best to have a static mixer down stream of the bleach injection. Then use a mixed media filter or a ceramic MF unit. When we do this in well waters, we inject the bleach into the water's pump suction. That provides lots of mixing.  You must have the pH around 8 and a minimum of 0.1 residual chlorine to get the Ferrous to ferric oxidation to occur quickly. A little jar testing will let you know what blend of bleach and caustic you need for this water. Enjoy