RK2 does make a smaller skimmer called the X-Flow I belive but I found for the smaller skimmers that the ETSS work good and the X-flow is more complicated than it needs to be. For large fishrooms and aquaculture there is nothing better than the big RK2 skimmers. I belive that the one that someone posted a picture of is a RK450 and runs 450gpm and the acrylic model shown is about $30,000.00 canadian