A stormwater treatment system for filtering stormwater, comprising: a deck stub connected to a drain conduit, a filter assembly including: a bottom; a center tube secured to the bottom; a hood secured to the center tube; and a filter medium located between the hood and the center tube; characterized in that: the bottom includes a boss; the center tube is secured to the bottom using a locking mechanism that inhibits relative movement between the bottom and the center tube, the center tube being in communication with an opening in the bottom; wherein to connect the center tube to the bottom, tube tabs are aligned to spaces between boss tabs and the center tube is fitted onto the boss, when the center tube bottoms out on the bottom, the center tube is rotated so that ends of boss tabs slide over curved surfaces of hooks on the tube tabs causing the tube tabs to deflect outwardly until protrusions on boss tabs move past the hooks and the tube tabs snap back radially inwardly; and the boss includes a rib extending laterally along an inner surface of the boss, the rib including a locking portion that mates with a corresponding locking portion on the deck stub for securing the bottom to the deck stub thereby inhibiting rotation of the bottom relative to the drain conduit. a deck stub connected to a drain conduit, a filter assembly including: a bottom; a center tube secured to the bottom; a hood secured to the center tube; and a filter medium located between the hood and the center tube; characterized in that: the bottom includes a boss; the center tube is secured to the bottom using a locking mechanism that inhibits relative movement between the bottom and the center tube, the center tube being in communication with an opening in the bottom; wherein to connect the center tube to the bottom, tube tabs are aligned to spaces between boss tabs and the center tube is fitted onto the boss, when the center tube bottoms out on the bottom, the center tube is rotated so that ends of boss tabs slide over curved surfaces of hooks on the tube tabs causing the tube tabs to deflect outwardly until protrusions on boss tabs move past the hooks and the tube tabs snap back radially inwardly; and the boss includes a rib extending laterally along an inner surface of the boss, the rib including a locking portion that mates with a corresponding locking portion on the deck stub for securing the bottom to the deck stub thereby inhibiting rotation of the bottom relative to the drain conduit. a filter assembly including: a bottom; a center tube secured to the bottom; a hood secured to the center tube; and a filter medium located between the hood and the center tube; characterized in that: the bottom includes a boss; the center tube is secured to the bottom using a locking mechanism that inhibits relative movement between the bottom and the center tube, the center tube being in communication with an opening in the bottom; wherein to connect the center tube to the bottom, tube tabs are aligned to spaces between boss tabs and the center tube is fitted onto the boss, when the center tube bottoms out on the bottom, the center tube is rotated so that ends of boss tabs slide over curved surfaces of hooks on the tube tabs causing the tube tabs to deflect outwardly until protrusions on boss tabs move past the hooks and the tube tabs snap back radially inwardly; and the boss includes a rib extending laterally along an inner surface of the boss, the rib including a locking portion that mates with a corresponding locking portion on the deck stub for securing the bottom to the deck stub thereby inhibiting rotation of the bottom relative to the drain conduit. a bottom; a center tube secured to the bottom; a hood secured to the center tube; and a filter medium located between the hood and the center tube; the bottom includes a boss; the center tube is secured to the bottom using a locking mechanism that inhibits relative movement between the bottom and the center tube, the center tube being in communication with an opening in the bottom; wherein to connect the center tube to the bottom, tube tabs are aligned to spaces between boss tabs and the center tube is fitted onto the boss, when the center tube bottoms out on the bottom, the center tube is rotated so that ends of boss tabs slide over curved surfaces of hooks on the tube tabs causing the tube tabs to deflect outwardly until protrusions on boss tabs move past the hooks and the tube tabs snap back radially inwardly; and the boss includes a rib extending laterally along an inner surface of the boss, the rib including a locking portion that mates with a corresponding locking portion on the deck stub for securing the bottom to the deck stub thereby inhibiting rotation of the bottom relative to the drain conduit.