These sight glasses from Evolution Aqua allow you to see what is going on in your plumbing, making it perfect for bead filters and other self-cleaning pond filters. Instead of going to the drain pipe output, you can easily see when your water is running clear. Simply cut away a piece of the exit plumbing from your filter and glue this sight glass into place. The clear pipe allows you to see inside, while the unions make attaching quite simple.
||Sight Glass, 1-1/2" Union Ends
||Sight Glass, 2" Union Ends