When your UV lamp is replaced it is recommended that the quartz sleeve that holds the lamp is removed and cleaned and the seals on this are replaced. So for those who are not sure of the setup here a brief explanation is as follows. There is a stainless steel chamber on most UV systems. Within this chamber which is either horizontal or vertical in a system contains a quartz sleeve which runs the length of the chamber internally. The quartz sleeve is a test tube, sealed at one end and open at the other. The open end is where the UV lamp is inserted. The UV lamp sits within this sleeve and is kept dry and protected from the water. The water entering the UV chamber spirals around this quartz sleeve and is exposed to the UV rays emitted by the UV lamp. At each end of the sleeve is a seal that prevents the water leaving the chamber. The UV lamp gets very hot when lit and over time makes the seals very brittle. The seals will if not replaced crack and your system will eventually leak. So annual replacement is suggested.
When removing the quartz sleeve for seal replacement it should be cleaned. This is done by gently washing the exterior of the sleeve with soapy water. An abrasive should not be used as this will scratch the outer surface and it is important to ensure no water enters the open end of this tube. A piece of tape is ideal to keep the water out of the open end. By keeping the quartz sleeve clean and clear you will be offering the best condition for the UV lamp rays to pass through the quartz sleeve and that will assist greatly with UV intensity and therefore water exposure.