You have the most beautiful pool! And complex! Maybe one or more of your drains plugged But if you can get a helper put plastic at different places while you change valves to try and see ways to troubleshoot your suction of air
Thanks very much, banditig. It's not nearly as complex or pretty as some of the pools here in Southern California, but it did take a fair amount of work to build. Knowing what I know now, there are a few things I'd do differently, but overall we've been happy with it.
The plastic idea is a good one. I'll try wrapping each valve one by one and see if it makes any difference in the air coming into the basket.