Algae in Filter's sight glass


Active member
Jun 11, 2010
Oakville, Canada
I've been successfully using the BBB method for over a month now. Recently, I went away for a few days and when I returned I noticed that there was some algae starting to form on the bottom of my pool. I shocked the pool and then noticed that the Sight Glass on the Filter has what looks to be green algae covering the bottom half of the glass. I backwashed for a couple of minutes and this didn't clear it up.

Is this a sign that there's something wrong with my filter or will the shocking process clean this part of the filter as well as the pool?


TFP Expert
LifeTime Supporter
Mar 29, 2007
Coastalish 'down easter'
Don't sweat the sight glass, it has water in which all the chlorine has been used up with no way to replace. However, it's not a problem because that water doesn't come in contact with your pool's water :-D

If it's for aesthetics, follow Bama's advice :cool: