Fluval AquaClear Maintenance Kit offers both forward and reverse water flow. The use of reverse flow through an under gravel system promotes bacterial growth from the bottom up, increasing biological filtration capacity. Supports efficient filtration Flow control Reverse flow option Aquarium rim attachment fits easily to all standard aquarium rims Solid, durable, compact pump construction Epoxy sealed motor Hermetically isolated from watera"fully submersible Water movement switch controls reverse and forward flow Fully variable output control suction cup bracket allows custom and deep installations Noise suppressor air filter quietly removes airborne contaminants before they can pollute Directions: Remove protective plastic bag (BIOMAX, Carbon) and rinse all inserts thoroughly before use. Maintenance: Replace foam insert every twomonths, Carbon insert every month, and BIOMAX every 2-3 months. Never replace all filter inserts simultaneously to ensure constant presence of beneficial bacteria. 30: BIOMAX (1 x 65g) Carbon (2 x 45g) 50: BIOMAX (1 x 125g) Carbon (2 x 70g) 70: BIOMAX (1 x 195g) Carbon (2 x 140g) 110 BIOMAX (2 x 390g) Carbon (2 x 609)