I added the shutoff below the skimmer as well. I had my pool professional installed ( ) and you would have thought this would have been something added that would be common courteous. I say that because it seems so obvious that you should have a shutoff there...but it isn't obvious until after the pool is installed and filled with water. How are new pool owners to know? if I had...I sure would have bought the shutoff valve before hand.

When I added the shutoff valve. I slowed down the water by removing the skimmer basket and placing a Tupperware container over the skimmer hole (like a cork in a bottle). This kept the water from rushing out as I added the valve.

good luck,
dan