Last year we did a nearly complete remodel in our master bath. We replaced everything but the tub. We did put in a new surround, replacing the sheet rock with green board first. What we didn't realize at the time is that the tub is apparently pitched incorrectly. Water stands in the back corner and so far, we have not been able to keep that corner caulked. Consequently, water is getting behind the surround again. Short of ripping out the new surround and properly pitching the tub, is there ANYTHING that can be done or is there a specific type of caulk that can be used that won't disintegrate from standing in water? I REALLY don't want to do another bathroom remodel just yet!