Well, I don't have the scientific answer, but I can tell you that I have two doodles and one swims daily. I couldn't keep him out of the water if I tried to do so. I do try to monitor the chemicals and keep them in the proper ranges, and I know that if you let your doodle swim in your pool you have to be careful that you monitor for phosphates in your water. The pool companies have told me that dogs swimming in the pool contributes to the phosphate levels in the water.
Joe swims multiple times per day in our pool in warm weather. He also has been known to take a dip in the middle of winter! He loves the water, and I have not had any issues with him swimming in our pool.