Something that I've wondered about is how much is actually pulled out versus how much is growing in the skimmer. I've moved lots of tanks over the years for people and an incongruity I've noticed is skimmers full of anaerobic stuff there are little or no anaerobic areas in the system. More importantly, research shows the DOCs (aka cabon dosing) that cause issues for corals are hydrophylic in nature so skimmer are pretty much useless for removning them. When I started my maintenance business in the mid '90s what stood out was it wasn't how much or how fancy the equipment, including skimmers, a system had that determined it's success, it was how consistant the maintenance, including water changes, was done. Skimmers seemed fairly superfluous.
What I consider more important, over the last couple decades there's been research across the board shown how critical healthy microbial processes are to the health of a ecosystems. We know skimmers are only able to pull out a subset of the microbial stuff. It's just the microbial stuff that is hydrophobic that can be removed. So we're looking at a peice of equipment that by the very nature it functions is altering the microbial stuff in the water guaranteeing disrupted microbial processes. So, yes, I consider skimmers detrrimental to the long term health of corals and reef ecosystems.
