Water treatment is essential for cooling tower recycle water, in order to control pathogenic bacteria such as Legionella.   Ozone, hypochlorite, bromine and chlorine dioxide to name but a few oxidizing agents are al used in cooling tower water to try and keep the bacteria under control.  The problem is that most of the oxidizing chemicals are volatile and are blown off out the top of the cooling tower,  or they are not affective against bacterial biofilm.

Water treatment is required  in order to improve the quality of the water and reduce the food supply available for bacteria, or the risk of fouling of the ion exchange beds  or membranes used in high pressure boilers.  Sand filtration is often used for this application,  however sand releases   free silica which can damage the membranes.  AFM (Active Filter Media) is  a direct replacement for sand in sand  filters and has the advantage that it does not contain nor does it release free silica. However the greatest advantage of AFM is that the media will allow your sand filters to remove up to 80% more solids from the water.  The lower organic / solids content, the lower the bacterial levels, which will reduce  the public health risk and biofilm induced corrosion of any metal work.

NoPhos is a perfect product for cooling tower recycle  system  because it removes phosphate, and when combined with AFM will greatly improve the quality of the water and almost prevent the growth of bacteria without the use  of any oxidizing chemicals,  or at least the chemical requirements may be reduced by up to 90%. APF is a flocculation chemical that contains PAC & NoPhos and is a useful combination as a pre-treatment prior to AFM sand filters.