Perlite for hydroponics: which fraction to choose

Why perlite suits hydroponics

Perlite is chemically inert, pH-neutral and sterile — it does not alter the nutrient solution and does not create an environment for diseases. When rinsed properly, it can be reused.

Comparing the fractions

The choice of fraction directly affects drainage and moisture retention:

• 0–3 mm — too fine, holds too much moisture, poorer aeration
• 2–6 mm — optimal: good drainage and aeration, suits most systems
• >6 mm — very good drainage, but dries out quickly

Usage tips

Rinse the perlite before use to remove fine dust. Perlite works great in drip and ebb & flow systems, as well as in mixes with coco coir or vermiculite.

To keep granules from floating, use net pots or cups with a perlite mix.