next to a ro unit a skimmer is the most important piece of equipment in your aquarium. get the best one you can afford you won,t regret it.mine is rated for a150gal.i use it in a75gal set up. i couldn't imagine using it in a 150 gal tank it seems it would be to small.i use ets downdraft skimmer with a mag7 pump.i never have to adjust it only keep the level in the sump the same.which i drip kalk.no beckett valves to adjust either. set it and forget it.