Changes

[[Image:granular high density carbon.jpg|thumb|right|250px|Granular, high-density carbon.]]

[[Image:filter sand.jpg|thumb|right|250px|Filter sand, supplied in bags and pallet packages. It consists of 99.5% SiO2 and is extremely low in trace metals and polycyclic aromatic hydrocarbons. This makes our filter sand the best sand available for monitoring well systems. Photo: [http://en.eijkelkamp.com/products/water/hydrological-research/groundwater-monitoring-pipes/filter-sand/filter-sand.htm Eijkelkamp Agrisearch Equipment BV.]]]