When reusing inert substrates, such as mapito, rockwool, clay pebbles, etc., you have to decontaminate the substrate due to the growth of plant-pathogenic (hostile) bacteria, fungi (think mainly of Pythium; better known as root rot), viruses, slime formation, deposition and crystallisation of salts, etc.

Substra Cleaner is the solution to this.
Use Substra Cleaner to rinse your substrate between harvests.
Substra Cleaner kills all plant-pathogenic bacteria, fungi and viruses in the substrate.

After rinsing with Substra Cleaner leave the substrate for 24 hours, after these 24 hours you can apply a nutrient solution to the substrate.

Substra Cleaner consists of hydrogen peroxide (H2O2) and within 24 hours breaks down into water (H2O) and oxygen (O2), that has a favourable effect on the root development of young crops.
If you want to reuse your substrate, Substra Cleaner is the proven solution to this