The buckets can hold up to 5 gallons and your choice of growing media. Its water tight seal guarantees no leaks. No need for expensive and tricky to use air stones. Pumping raw air into the nutrient solution is cost effective and helps your plants to thrive. The pump sends air shooting through the multi purpose air hose into the bottom of the bucket, where it then oxygenates your water to enhance root growth. Enjoy this easy to use, inexpensive, and forgiving system, the Active Aqua Root Spa.