Over the last few months they has been a fair amount of talk on UV sterilizers. I have just ordered one of these:
AA Internal UV Sterilizer 9 Watt
http://www.aquaticlifeaquariums.com.au/
as i would like to trial on a tank of discus.
they seem a lot more $$$ than the external ones that attach to the outflow of a cannister filter but then a cannister filter is not needed.
If anyone has one/used one or knows about them i would love to hear about it!
Thanks in advance,
Ben