Description

The Waterway 873-E17S1 is a replacement sight glass, the clear window fitted to a filter valve so you can see the water going through it.

What you use it for

When you backwash, water leaving the filter starts dirty and gradually clears. The sight glass is how you know when to stop, rather than guessing at a time and either cutting the backwash short or dumping more water than the job needed.

Before you order

Waterway classes this as a filter valves part and catalogs it with the 2 inch side mount Crystal Water DE filter valves WVD001 and WVD002. Sight glass sizes and threads are not interchangeable across valve families, so take the old one out and compare it before ordering.