Been doing this for years now. Probably about the same time as the BRS video came out about it.
I use just a plain 1 micron sediment filter, same ones I get for my RO/DI. I change it out on a yearly basis. They are always brown, but I never have added head pressure, and pretty sure I could go longer then a year, but I feel a year is long enough.
I have mine running from the start on a closed loop sort of setup on my mixing barrel. The salt mixes in like normal, nothing is left in the filter.
I use regular old purple box IO, and my mixing barrels are spotless same as they were on day one.
From the first time I used it, I was very surprised about what it caught. Not just the "brown crud" but flecks of metal, small flecks of plastic, and god knows what else.