My 2.5 cents again

You can also rig a sterilizer with an external power filter. I take water from the
post filter media side, run it through the sterilizer and then put the output back
in the tank at the other end. I regulate flow with a "pinch" type collar that is
made for this. $ months and it works great. (I did it this way because I had the
power filter first. I use the clean water filter input instead of just drawing
from the tank because it is (should be) cleaner)

LeighMo wrote:

perhaps a more powerful UV sterilizer?

No. A UV sterilizer will take care of green water, but it will *not* fix other
algae problems. The best way to control algae is to keep your nutrients
(including CO2) in balance with your lighting and your plant selection, and to
keep some algae-eaters for mop-up.

are the steralizers inline with the filter or how do they work?

There are two kinds of UV sterilizers: inline and standalone. Some can be used
either way.

The inline models are meant to be used with cannister filters. You just hook
it up "inline" with the cannister filter, and the cannister filter's pump runs
water through it. (You should get a T-connector, so you can control the amount
of water that goes through the sterilizer.)

The standalone models are meant to be hooked to a powerhead, which you must buy
separately. (Check to make sure the flowrate of the powerhead is within the UV
sterilizer's recommended flowrate.) Get a standalone if you'll be using the
unit on more than one tank.

I bought a Custom Sealife "Double Helix" model, which is one of those that can
be used both inline or standalone. (I'm using it standalone, with a Penguin
powerhead.) I chose Custom Sealife because it's lower maintenance than most.
With other sterilizers, you have to wipe algae off the quartz sleeve over the
bulb every once in awhile. With some types, this means dismantling the unit to
clean it. Others have a "wiper," that allows you to clean the sleeve without
taking the unit apart, or even taking it off the tank. The Double Helix
doesn't have a quartz sleeve. It's made out of special polymer that's so
slippery algae can't adhere, so there's cleaning.

In addition to cleaning, you have to change the bulb regularly, or the
sterilizer won't be effective. The interval depends on what model you get --
generally, it's anywhere from every six months to every eighteen months.

Also make sure the sterilizer you choose is sized for your tank, and that you
have the proper flowrate going through it. I recommend sizing up one;
sometimes manufacturers exaggerate the effectiveness of their units. And ich
can be tough to kill.

Leigh

http://www.fortunecity.com/lavender/halloween/881/