I have a Realux Daylight T6 in place of my original Juwel 15watt 18" T8. I can't say it as particularly 'brighter' than an 18" Interpet Daylight Plus T8 that I also tried, but I did get an algae sppike from the T6 that was only cured by dropping the lighting period from 10hrs to 7.5hrs. Plants are certainly doing well and both the Interpet T8 and Realux T6 are much much better than the Juwel tube supplied with the tank: they are brighter to the eye in this respect.
goodo.. good to find someone who has tried it..
Also.. lets be honest, any tubes that replace the standard juwel ones are a plus!!! Dimmer than Jade Goody
Squid