I thought i'd share my recent experience with UV sterilizers.
Most UV sterilizers are rated for their wattage as follows:
-Treats up to __Gallons
-For use with a flow rate between __ and __ GPH
Well, keeping those two criteria in mind i purchased a UV unit to combat a recent experience with green water.
The particular unit i bought had the following criteria:
-Treats up to 125 Gallons
-For use with a flow rate between 200 and 400 GPH
I have a 50 gal. tank with roughly a 350 GPH cannister filter. Sounds like it would work right? Not in all cases.
Here's a lesson. Read the manual in its entirety before you begin. I hooked up the unit thinking there wouldn't be any problems. On the last page of the manual (after the unit is installed and running) there is a nice graph on flow rates and UVC energy. To simplify, the wattage of this particular unit is effective on parasites when GPH < 500, algae when GPH < 240, and parasites when GPH < 110.
So.... it turns out the criteria listed on the box isn't all that accurate. My flow rate of 350 GPH from my filter is too much to combat algae (i tried just to make sure, but no luck)
Well.. i solved the problem by using a powerhead (just what i needed... less room in my tank) attached to the UV unit and it seems to be working fine.
It's important to consider your particular application when determining the wattage required.
This is the best article i found even though it contradicts some of the other articles listed on this site: http://www.drsfostersmith.com/pic/ar...id=423&aid=837
Hope this helps!