I use an Aqua 25w UV
sterilizer on my 125G planted tank and I love it. I have never had GW or a single sick fish *knocks on wood*. UV
units are most commonly used in-line with a canister or sump filter system. UV
is capable of doing two things: at low levels (either low wattage or a very short dwell time) it can clarify
the water (as mentioned above) by wiping out GW and other floating algae; at high levels it also sterilizes
the water column, meaning it kills (disrupts the nucleus of the cell structure with ultraviolet radiation) bacteria, fungus, and even some viral organisms. If you do go with UV
, make sure to purchase it with your purpose in mind. Too weak and you will likely only see clarification of the water so buy accordingly. Aqua is the best brand I've ever used and I highly recommend them.
A few notes:
sterilizers should not be used on tanks that are cycling because they will inhibit the spread of free-floating nitrifying bacteria and increase the amount of time it takes for your bio-filters to mature.
2] I have had great luck running my UV
sterilizer only during lights out (roughly 12-13 hours a day). It still kills free floating nasties and the bulb life is basically doubled.
3] I've never seen conclusive evidence of this but I have heard that UV
radiation can oxidize iron and other trace elements in the water column. Only planted tank keepers need be concerned with this. In my case, since I run the UV
only during lights out, I dose Fe
and trace first thing in the morning, right after the UV
has shut off, thus giving my plants a full daylight cycle to absorb trace nutrients before it kicks back on and (possibly) oxidizes all of the goodies.
4] Consider purchasing a unit with a built-in squeegee (Aqua sells them) so you do not have to disassemble the unit to clean the quartz sleeve that houses the UV
bulb. With an in-line system this is a real time-saver.
I hope this doesn't make UV
sound like a hassle because, IMHO
, it has been nothing but good for me. I wouldn't be without it on a big tank. It's good stuff