Got a pool and waterfall going in in southern AZ. The waterfall guy is putting Hycrete into his shotcrete and tells me that's all that is necessary for waterproofing (no pebbletek in the waterfall area). The pool guy tells me the pebbletec is the waterproofing layer in the pool. Just watched a pool going in on TV and they put some sort of coating over the shotcrete to "waterproof" it before the pebbletek. Am I missing a layer here?