What next, nose clip?

I'm swimming with a new workout group this year, and am thus in a new pool. Something in the water (not necessarily chlorine) is giving my sinuses fits. It takes more than a day to unstuff, during which time sleeping is problematic. I've rather casually tried decongestant (currently only Sudafed PE) and antihistamines (Claritin) and my trusty neti pot. The neti pot doesn't help a lot if your sinuses are completely clogged though. I'm skeptical that it's chlorine causing problems mostly because I swam in an older pool last season which had higher chlorine levels with no problem (at least by how long the chlorine smell lingered on my skin). I realize that chlorine is an irritant, not an allergen, so maybe antihistamines or decongestants won't be all that effective. Is there a nose clip in my future? Anybody using a nose clip strictly to keep chemicals out of your nose and sinuses? Thx, Skip