Our high-performance REEFER™ Skimmers feature a combination of PSK pumps with proportionally sized venturi, bubble diffusor and reaction body that optimizes air-water contact time for steady waste removal.
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It also depends on how much you are changing out your filter socks.
I think the number they give is the max tank size under low load
(usually they say low, medium, or heavy bioload and then say size with low load being the largest tank size)