Yes, when you mix in smaller particles you restrict the air space and moisture is held longer. When you are trying to maximize aeration of the roots, uniform, round particles are the best. But, you then need more frequent water flow. That gets into Ray’s question about hydroponics, semi-hydro, etc. You wouldn’t want to use medium sized, uniform, round LECA and then water once a week with nothing in between. Most orchids would probably be too dry.Respectfully I don’t really know about that because in my round Leca pellets, there are different sized pellets in the bag. How do round pellets fit together versus uneven pellets? I tried plain Leca in Florida, it was a bit too dry.
By mixing in charcoal and perlite, I thought it held moisture a bit better.