LECA, standing for "Lightweight Expanded Clay Aggregate," is a general term for any number of more-or-less spherical terra cotta pellets that were originally designed to be the aggregate in lightweight concrete formulations, but later diverted to horticultural use. There are many brands available, including Aliflor, Hydroton, PrimeAgra and others, and they vary greatly in their properties and applicability to orchid culture.
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