Fishtruck, I don't think you will see much, if any, water lifted from below the diffuser strictly due to the 10" pipe below it. Water will be drawn upward from below the diffuser by default without a pipe, but how far below is the question (not much movement at 5 feet below the diffuser I'd bet). Now, if you could run a large enough pipe to put the diffuser into (with enough extra room around the diffuser so water could pass it) that had the pipe below AND above it...it would pull water from below due to the upward draw of the air bubbles in the pipe section above the diffuser. For example, 12 foot vertical pipe with the top of it at 1 foot below the surface and the diffuser 5 foot below the surface would pull water up from 13 plus feet below the surface.
