 This replacement was made after several complaints by players and managers that the pitch was excessively hard and far too slippery.Since January 2006, a special growth and lighting system called the SGL Concept has been used to assist grass growing conditions, even in the winter months.The system, created by Dutch company SGL (Stadium Grow Lighting), helps in controlling and managing all pitch growth factors, such as light, temperature, CO2, water, air and nutrients.