Draining to just above the basket and then adding fill water will work, but it will be very slow. Assuming you're wanting to drain 1/2 the water, I would say 3 or so drains of 1/4 would work. Otherwise, I've seen reference to the "sheet method" (can't remember if it's CarlD or Poconos that has used it) where you put a sheet of plastic on top of the water and drain from under the sheet as you fill on the top--it's supposed to keep the chems in the top and bottoms from mixing.

Here's an old thread that talks about the sheet method--see ChemGeek's reply toward the bottom of the thread..http://www.poolforum.com/pf2/archive...hp/t-6121.html