Grodan 7.5x7.5 - Cubes rock wool

The Grodan 7.5x7.5 is the most used substrate for hydroponic cultivation. This inert material, commonly called rock wool, is obtained from the merger and processing of certain types of rocks and presents a high porosity (approximately 96% of its volume) and a conspicuous water retention capacity (up to 80% of the volume.
These characteristics make it widely used for germination and cutting operations which as well known require an inert substrate, well oxygenated and with excellent absorption capacity. The rock wool cubes are prepared by immersing them for about 24h in a water solution with pH between 5 and 6. Prepare the Grodan 7.5x7.5 with pH solutions of 5 of 5 can generate various problems due to an alteration of the structure.