Unfortunately, low flow / low suction is one of those pool problems with many possible causes. Here are a few:
+ Air leak in suction piping, weakening pump's suction.
+ Clogged impeller (pebbles, pine needles, etc.)
+ Clogged or damaged strainer basket.
+ Kinked suction piping.
+ Damaged or failed valve that looks open, but isn't. (Both ball and gate valve stems can break)
Bookmarks