Sucking Out Lines

[CanuckPool]

Just had my pool closed by the builder (first year with pool) He dropped the level of the water just below the level of the returns and used a shop vac to suck the lines out, he says he prefers this method since he says he can be sure all the water is out of the line. Any thoughts on this. He has been using this method on the hundreds of pool closings he does so I guess it must work.

[Poconos]

Since the water is drained below the returns I don't think it should matter which way the airflow is going. Sorry it took so long to answer...was away for a bit.
Al

[JohnT]

Don't see that it makes any difference. Still going to leave a little water in there unless the pipes are completely level or sloped in one direction.