I have used them.... not used them...... and am going back to using one! :doh:
I think if you a using to fight parassites and diseases or serious algae issues....then you are getting it for the wrong reasons. As the effectivness of a UV for this will not work unless you have very high turnover and a huge UV Bulb .
The reason I am going back to the UV is I noticed an increase in film growth on the acrylic w/o the UV. Meaning I need to run the Mag Float more often! No alga issues however:banana:
I have never had any parasite or algae out break, w/ or w/o the UV though.
Also I have noticed the water to be a little clear due to UV use!