I am bare bottom. I used to have a Euroreef RS250 rated for 250g and no matter what I set it to, skim wet or dry, it would always pull out nasty stuff. Macro algae would also grow rapidly. I then decide on the BM250, since then macro has decreased drastically and skimmate almost double in quantity. This skimmer is still pulling out as much nasty stuff as it did the first week. To me that's is a sign that the skimmer performance is at par with the waste output of the system. If it was too effecient for the system, I would get light skimmate or very little, but that's not the case after 10 months of use. So IMO it can't be effecient for a tank more than twice my size. Not much has changed in terms of livestock, feeding routine (small once a day), maintainance procedures.