Does anyone KNOW if this is really true, and does anyone here replace their sleeves on a regular basis ?
mind you, this "knowledge" comes from folks that SELL sleeves

sake good order, one of the largest wholesellers in Europe, SIBO, claims this degradation thing
http://www.sibo.nl/pdf/Engels/07%20UV" onclick="window.open(this.href);return false;%2 ... ENGELS.pdf
where it says
Quote :
UV-C TL LAMP SET code 805
Complete set with high quality TL lamp (10.000 working hours!),
quartz sleeve & O-rings. For optimal results it is better to replace
the quartz sleeve on a regular basis. A quartz sleeve does wear
out and exposes already 25% less radiation after 1 year of use!
Unquote
/Flemming