The Under Current® Systems are ideal for large-scale commercial growers. With the patented Sub-Current Culture® circulation method, growers can now improve operational efficiencies and overall yields. Sub-Current Culture® (SCC) technology utilizes negative water pressure to recirculate highly oxygenated nutrient solution through the plants root zone. This continuous fluid motion supercharges the nutrients with dissolved oxygen, creating hyper-aerobic conditions perfect for explosive plant growth. High levels of aeration and constant circulation optimize plants nutrient uptake capacity. This action conserves nutrients, water and necessitates less frequent nutrient change-outs. 30 inch plant centers with recommended growth time of 3-5 weeks. The Under Current® XL13 & XXL13 Systems Includes: 30 in center in the 13 gallon Blackout Series growth modules, 3 in manifolds, 3 in UC Spin Tight Bulkheads, 8 in heavy duty lids with port hole, heavy duty 8 in net pots, Danner Mag-Drive Return Pump, Premium Linear Air Pump(s), 9 in air diffuser disc, Aqua-Pore Air Diffusers, air distribution manifold, air hose, in-line filter(s), adjustable float valve with reservoir adapter kit, drain valve, dhiller adapter, garden hose drain adapter, Cultured Solutions VEG A/B. 16 site has a 15 ft x 16 ft grow area, 24 site has a15 ft x 22 ft grow area and 32 site has a 15 ft x 28 ft grow area. These items are drop ship only.