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If you want to eliminate the plumbing, perform a vessel test. Turn off the pump, plug ALL inlets and outlets from the pool and mark the waterline in the pool. Concurrently, partially fill a bucket with water and mark the level and set it on a step. The next morning compare the water loss in the pool to the water loss in the bucket (any water loss in the bucket is due to evaporation). If the pool losses more than the bucket, you've got a leak in the vessel/ liner. If the loss is the same, it's a plumbing/ equipment leak.

If you can do this test and report back, as to the results, we'll help you narrow down the source