The EC value of water indicates the amount of nutrients (mostly calcium) present in it. When you add liquid nutrients to water, the EC value will rise. We recommend a maximum total EC value of 3.0. Higher values can lead to nutrient burn.
Two sizes? Why's that?
Not all plants need the same amount of space. 8 L growbags are ideal for bigger plants and provide more room for root growth. The 3.4 L growbag is perfect for smaller or compact plants with shallow roots.