Typically capillary action is the enemy of drainage. The most extreme example is bentonite clay formed from extremely fine airborne volcanic ash. The capillary action is so strong that it is used in geo-fabrics to line waste sites to prevent water exfiltration. Tim Normally for my purposes, and in my climate, I want maximum capillary action through my pots and into the surrounding sand. Peter (UK) On 23 January 2015 at 16:32, Alberto <ezeizabotgard@hotmail.com> wrote: > And even better if you mix all coarse materials and put no fines at all.