Let's hope it holds.Hey eplumber! I just tried a small balloon for my shower pan liner test. It seems to be holding back the water just fine. I happened to have some old small water balloons and blew one up to about 2.75 inches in diameter (my drain is 2") and worked it down into the drain past the weep holes. I added water tonight and will check it tomorrow after work. Just saved myself $20 to $30 dollars by not buying a test ball plug.