Algae Prevention


No.85 Algaecide

No.85 Algaecide

Video Overview


No. 85 Algaecide, is a polymeric, cationic biocide that has been developed for controlling the growth of algae, bacteria, and fungi in recirculating water systems such as cooling towers, evaporative condensers, closed cooling water systems and industrial air-washing systems.

Algae are microscopic plants that grow rapidly in cooling towers, spray ponds and other recirculating systems exposed to sunlight. These free-floating growths can be carried to the condenser or heat exchanger by the condenser or heat exchanger by the recirculating water where they lodge and act as binders for sludge and suspended matter. In addition, algae can contribute to the formation of slime deposits by providing organic matter necessary for the growth of bacteria. These biological growths restrict water flow, reduce heat transfer efficiency and increase head pressures, all of which result in lower efficiency and increased power and service costs. Treatment of recirculation water with No. 85 Algaecide prevents growths of algae and bacteria from developing to the point where they cause the problems described.

NOTE: This product is not registered for sale in Canada.

Packaging Size Part Number
1 Gallon Bottle 4108-08
15 Gallon Bottle 4108-P3


Initial Dosage: When the system is just noticeably fouled, slug 1.9–4.75 ounces of No. 85 Algaecide for each 1000 gallons of water in the system to provide a concentration of 16–40 ppm of No.85 Algaecide. Repeat until control is achieved.

Subsequent Dosage: Subsequent additions of 0.47–4.75 ounces of No. 85 Algaecide per 1000 gallon of water (4–40 ppm) should be employed on a continuous basis through use of the Nu-Calgon Wholesaler Drip Feeders. Use 1/6 of a gallon per month for every 50 gallon per hour of bleed off that is being maintained on the system and the recommended residual (4–40 ppm) will be achieved.

Click on "Product Information" and download product bulletin 3-41 for more details.

Literature Downloads

Download the product bulletin and other relevant literature here.

SDS Information

Read and understand the product’s Safety Data Sheet for precautionary and first aid information.