Where did all the water go?

You just can't tell a man about his pool. For some time now I have been putting what seemed like an inordinate amount of water in the pool. I finally decided that it was leaking, and so stopped filling it, and let it settle to its natural level. The level stopped falling just below the skimmers, so in my mind the leak had to be above that level. Seemed simple enough to me. So I call in my 2 experts, both called Manu. One a Portuguese builder and the other a French plumber. What do they think? They both give me conflicting advice and neither agrees with me that the problem is at the skimmers. I'll need some convincing on this one.

With endless patience I insisted that we remove the covers to the skimmers, and, well blow me down, there's enough evidence to show the truth. So who's a clever boy? It will be fixed tomorrow, when I'll clean the pool and start the heating, and then Jan can start her lengths. Hopefully, she'll do enough for the two of us!