Filtration to Eliminate <i>Phytophthora</i> spp. from Recirculating Water Systems in Commercial Nurseries

Fig. 2. Slow sand filtration (SSF) systems: (C) completion of gravel layers prior to filling in an earthen basin with sand.



Image from Plant Health Progress article:
Filtration to Eliminate Phytophthora spp. from Recirculating Water Systems in Commercial Nurseries