Today is Independence Day! And of course the pool store is closed. And I broke the sight glass on my sand filter. I'm about to go out of town for a few days and didn't want to shut everything down and have a frog pond when I got back. (I'll have frogs anyway because I live on a swamp, but that's different.) Since necessity is a mother, I hunted for something to work until I got a new sight glass...and like this even better! It is a salt pool, after all.