Cephalotus Soil Mix: Substituting Pumice with Silica Sand

Nicole (90 mi north of NYC) can't source pumice for the recommended 1:1:1 peat/perlite/pumice Cephalotus mix. She tested aquatic plant soil (fired kaolin clay)—pH stable at 5.4, but TDS jumped from 18 to 136 ppm after soaking.

Rinse and Retest

Soak and rinse the aquatic soil several times. If TDS remains elevated, switch to silica sand ("Commercial Grade Sand" at Home Depot)—cheap, available, and excellent for CP mixes. If TDS normalizes after rinsing, the aquatic soil is fine (residual manufacturing dust).

Why Not Vermiculite?

Vermiculite holds too much water and breaks down. Silica sand provides drainage and aeration without pH drift.