We just closed on a house today and I'm trying get a handle on how the filter setup works. I'm pretty well sorted except I'm not sure what the white valve in the middle does. I assume it's the ratio of skimmer vs main drain but the markings on the valve are worn off and not readable. The skimmer is coming in on the left and the main drain is coming in on the right but not sure which way does what. Also, see the black pipe sticking straight up in front of the chlorinator? Any idea on what that might be? I sprayed some water in it to see what would happen and now it's just full of water, it didn't drain out anywhere
Link to picture: http://i.imgur.com/vxyxLku.jpg
Link to picture: http://i.imgur.com/vxyxLku.jpg