I'd love to treat this as a game, but thus-far locating the source of our pool leak has been anything but fun. We're renting a house with an in-ground vinyl pool about 30k gallons (105,000 square inches, average 5.5' depth) and just opened the pool about a week ago. The pool guy who opened it noted that the water level looked "a bit low" as compared with other pools he opened this season as we had a very wet winter.
The pool has two skimmers, three returns, and no main drain. The pump is located above water level, and there is a switch valve to control the skimmers (1, 2, or both). The multivalve is a bit old, but does not appear to be leaking out the waste line. (The waste goes out to the street, and there's no sign of water there unless we're backwashing or set to 'waste').
Now that we're open, the pool will not maintain a water level anywhere above the bottom of the skimmers. I ran the bucket test both with the pool running and turned off, and in both cases the water level drops dramatically from mid-skimmer to the bottom edge within 12 hours... losing about 600-1000 gallons.
Fortunately the water isn't finding its way into the basement, and so far we have seen no signs of where the heck it's going. The pool guy suggested the most likely cause would be a crack in one of the skimmer boxes.
Is there any way to test this to identify what's really going on? The only thing I can think of is to devise some method to block the skimmer closed and pour water in from above and watch how it drains. But I have no idea how to effectively block the skimmer to run such a test. I'd love to say, "there must be an easier way", but maybe that's why leak specialists get paid the big bucks.
Any assistance or commiseration would be appreciated!