Low versus medium pressure lamps

There are two types of UV lamps—a low-pressure, high-output lamp, which emits UV rays at a maximum of 254 nm, and a medium-pressure lamp, which emits UV rays between 200 and 600 nm.
Generally, low pressure lamps are better suited for residential applications, while medium pressure lamps are typically designed for large commercial installations. The distinction can be chalked up to cost, flow requirements and the ability to destroy chloramines.
Due to its large light spectral, medium-pressure lamps are more effective at reducing chloramines and improving air quality.
Wattage
Compare the wattage needed to provide proper water flow treatment, as consumption varies between different products. Further, by using a system equipped with an electric ballast additional savings can be attained, as it prolongs the life of the UV bulb and uses less energy.
Spare parts/maintenance

Depending on the warranty program, some UV systems may require substantial maintenance and require routine servicing. For this reason, be sure to inquire about the pricing of spare parts and any required maintenance costs, as this may vary by manufacturer.
Cost/payback
By using less chemicals and providing a safe bathing environment, a UV sanitation system will pay for itself many times over in comparison to traditional water treatment methods. Depending on several variables (i.e. water quality, bather load and the facility’s filtration system and installation), the return on investment (ROI) is often less than one year.