What is an evouv quartz sleeve?

It’s a tube that looks like it’s made of glass, which separates the pond water running through the unit, from the bulb. It’s very delicate, like glass, and should be handled with extreme care. Quartz sleeves should be cleaned regularly to ensure that the UV rays can shine through it, and do their job on the pond water. A dirty quartz sleeve will negatively affect performance. If a quartz is cracked or chipped, it must be replaced.