Hi rcheng,
I modified the last canister chamber in my Crystal Pro a la May&Bruce's method for DI resin. See May&Bruce's attached pdf documentation in the link below.
http://www.sgreefclub.com/forum/index.php?showtopic=42927
I brought the whole canister to a plumbing shop somewhere in Ubi industrial estate. The owner was kind enough to entertain my small request.
He found a PVC pipe that would almost fit & sawed off a 1 foot section for me for a token $2.
All I had to do when I got home is to file down the rough edges on both ends. After which, I lighted a candle to heat up the inner surface of one end to expand it a little. Then quickly attached it to the canister cap while it's still expanded. (The length of the PVC pipe has to be short enough so that water can flow out at the bottom of the canister.
THAT'S IT!
My TDS reading is 0ppm.
Good luck