prepare an acidic solution and spray it over the tower surface, fills, fan etc.. the solution penetrates deep into the tower packing cleaning, descaling and disinfecting as it progresses through the tower. Bi-annual cleaning is very important because dirty water in the cooling tower causes legionella, the primary bacteria in legionnaires disease. It also fouls chillers, robs heat exchange efficiency and drives up energy costs and scale ridden fill can be a biological nightmare.