My understanding is that they have to be fairly large in order to be effective. I'm "only" running ~2,000GPH through my sump but I think that flow rate is too high to run a settlement chamber given the 150G volume of my sump. I think I would need a large separate container for anything to really "settle."
In regards to a drip system, I really like the idea, just not an easy option for me. There's no easy way for me to set one up without some major work. In addition to lacking the plumbing to the location of the tank, my tap water is treated with chloramines, so I would either need a prefilter or dose conditioner to neutralize the chlormaine (both options seem risky to me).