... free.3,Modular with plug-in design, easy maintenance, reliabilit.4,Use Ozone-specific air pump, longe-lived and good stability.5 ... cord.7,Three colors of the aeration stones of different shapes to meet different application requirements, more humanization.8,Two ... 90%Reduces decay processes in wastewater, fishponds and other organic contaminated ponds or Canals.Improves the filter efficiency by 80% ...