One type of sea life has proven tough to keep in home aquariums: jellyfish. The blobby beasties get shredded like Kleenex in the filters. This 7-gallon tank — a project that got funded through Kickstarter — solves that by using a laminar-flow system to circulate the water in a controlled swirl, nudging the jellies to the middle of the tank and away from danger. The kit takes about 10 minutes to assemble and includes a voucher for three moon jellyfish, shipped overnight in Styrofoam coolers along with a six...