Life span

permanent

replace every 2-5 years

PH adjustment

unnecessary; mineral content buffers pH

may need periodic adjustment

Airflow

consistent over time, even distribution

Back pressure increases over time, air-channeling can occur

Hydration properties

hydrophilic; readily absorbs water, even after extensive dry periods

hydrophobic; difficult to hydrate after drying out

Cost

one-time low installation cost

recurring costs to remove and replace every 3-5 years