Hi, I've been reading the discussions about nematodes and have a question: what kind of potting soil is best to use? Will it get the water all cloudy or settle after a few hours? So far I've been using regular gravel to grow my plants in and plan on adding crushed corrals, since our water is super-soft. Advise anyone? TIA, Ivon in Fayetteville, where the Dogwood trees and Azaleas are in full bloom