The Under Current? XL13 and XXL13 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 plant?s 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. 40 inch plant centers with recommended growth time of 4-6 weeks.The Under Current? XL13 & XXL13 Systems Includes: 13 gallon Blackout Series growth modules, 3 in manifolds, 3 in UC Spin Tight Bulkheads, CCH2O 8 in Heavy Duty Lids with Port Hole, CCH2O 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, Chiller Adapter, Garden Hose Drain Adapter, Cultured Solutions VEG A/B. These items are drop ship only.