I highly reccomend the Aqua Ultraviolet brand...This company has been making nothing but UV sterilisers for many,many years.They are without a doubt the best on the market(imo)...Also,make sure to get one with the quartz sleeve,and wiper.The sleeve makes them more effective,and bulb repacement can be done without shutting the entire system down and spilling water everywhere.and the wiper makes it possible to clean the sleeve without taking the unit apart...I have the aqua 25 watt on my 130,and love it.....