Sight Glass has green algae visible


Bronze Supporter
Sep 17, 2016
Dallas, Texas
Hello TFP friends!

First let me say again what a great wealth of knowledge for pool owners. Many kudos to those that created it and keep it running!

I've just noticed for the first time that there is algae visible in the backwash sight glass. Is this normal? How should i address it?


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Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
Tucson, AZ
Happens in mine too, it should only see what when backwashing, then the water is trapped and algae can grow. Just unscrew it and clean it out of it bothers you.

I think it should eventually dry out. If it does not, then the valve could be leaking a little to backwash. Pull the vial off and leave it off and see if there remains water in there.