A common application of aquaponics today is raft (deep water culture) aquaponics, in which water from the fish tanks flows into a series of solid filtration and biofilter tanks, which respectively serve to remove large solids and use bacteria to break down ammonia into nitrate.From these tanks water flows through the plant beds before returning to the fish tanks. To create a stable ecological system and maximize crop and fish production, aquaponics practitioners now control a variety of factors such as the water temperature, pH, micro- and macronutrients, dissolved oxygen, and sunlight/photo-period. Several studies have attempted to optimize various factors and report the commercial production associated with these optimized states and much of this literature has been reviewed by