It's difficult to be sure that what you see are parasites, lots of stuff gets stuck in the folds of the bowels.
The Coffee sold by http://www.sawilsons.com/ is far easier to hold so that may be an option. Also if you use distilled water that seems to help a lot.
Another option is to do more than one, a small one to help empty out then a larger one to follow. Dr. Kelly has a different view and doing the enema his way means doing two or three 250-300ml enemas instead of a large one.