The WaterFram 8-pack is eight WaterFarm module units connected to one General Hydroponics Controller- an integrated 13 gallon reservoir and an 8 gallon controller unit. The controller will keep each unit topped off with the correct level of nutrient for low maintenance. The WaterFarm 8-pack is powered by GH's Dual Diaphragm Air Pump and includes necessary hardware and Flora Series nutrients. The grower can arrange the WaterFarm units in a design that is suitable for any environment. Pack them tight or space them out for your growing situation. The WaterFarm 8-Pack is the system for big growers. Clay pebbles not included. You'll need about 70 liters of hydroton/ clay pebbles to fill a WaterFarm 8-pack.