i use a sump made by marine life aquatics in tandem with one of his skimmers. it is great for the needs of my small system, and has the capacity to handle up to 150 gallons to work with my next upgrade.
MLA makes both trickle and berlin style sumps in a variety of sizes for most aplications.
their website does not have direct sales, but it does have links to retal places, or you can search on the net, when i did i got a couple of links for resellers.
marinelifeaquaticsdotcom
you can buy it from the same place i did by searching for souta's saltwater and getting their contact information