Editing Hydroponics (section)

===Rock wool===
[[File:Rockwool 4lbs per ft3 fibrex5.jpg|thumb|upright|Rock wool]]
Rock wool ([[mineral wool]]) is the most widely used medium in hydroponics. Rock wool is an inert substrate suitable for both run-to-waste and recirculating systems. Rock wool is made from molten rock, basalt or 'slag' that is spun into bundles of single filament fibres, and bonded into a medium capable of capillary action, and is, in effect, protected from most common microbiological degradation. Rock wool is typically used only for the seedling stage, or with newly cut clones, but can remain with the plant base for its lifetime. Rock wool has many advantages and some disadvantages. The latter being the possible skin irritancy (mechanical) whilst handling (1:1000).{{Citation needed|date=April 2016}} Flushing with cold water usually brings relief. Advantages include its proven efficiency and effectiveness as a commercial hydroponic substrate. Most of the rock wool sold to date is a non-hazardous, non-carcinogenic material, falling under Note Q of the European Union Classification Packaging and Labeling Regulation (CLP).{{Citation needed|reason=reliable source|date=October 2012}}

Mineral wool products can be engineered to hold large quantities of water and air that aid root growth and nutrient uptake in hydroponics; their fibrous nature also provides a good mechanical structure to hold the plant stable. The naturally high [[pH]] of mineral wool makes them initially unsuitable to plant growth and requires "conditioning" to produce a wool with an appropriate, stable pH.<ref name="Alexander 1994">{{cite book |title=The Best of Growing Edge |date=1994 |publisher=New Moon Publishing, Inc. |isbn=978-0-944557-01-3 }}{{pn|date=March 2025}}</ref>