There are various brands of LECA out there that wick as well as pumice, but perform better in terms of maximizing the air flow to the root system. That is controlled not only by the space between particles, but the surface porosity of the medium as well.
Look at it this way: the coarse surface porosity of the pumice I've seen (very like that on lava rock), tends to hold "droplets" of water right at the surface. When two pieces are in close proximity, their droplets can bridge the gap between them, which effectively makes the free air space smaller. A good quality LECA, on the other hand, does not have the coarse surface porosity (they have extrememly fine pores at the surface), so the bridging is less prominent. The space between particles is also usually improved with LECA, as they are manufactured to be uniform in size and more-or-less spherical, which is the best you can do. With pumice, unless you're lucky enough to hand-pick the particles, the packing can be denser, hence less open to air flow. -- Ray @ First Rays Orchids Original Message: ----------------- From: Olga Caussade [EMAIL PROTECTED] Date: Mon, 2 May 2005 19:21:26 +0200 To: Orchids@orchidguide.com Subject: [OGD] Re: Pumice Hi Ray, Thanks for your answer, but what did you mean by something better? I mean staying in a mineral selection. Thanks for your help Olga _______________________________________________ the OrchidGuide Digest (OGD) orchids@orchidguide.com http://orchidguide.com/mailman/listinfo/orchids_orchidguide.com -------------------------------------------------------------------- mail2web - Check your email from the web at http://mail2web.com/ . _______________________________________________ the OrchidGuide Digest (OGD) orchids@orchidguide.com http://orchidguide.com/mailman/listinfo/orchids_orchidguide.com
