Although the disposable enema units you purchased were labeled as "saline" they are not the standard traditional NaCl (Sodium Chloride) and water solution we generally refer to as saline.
Fleet and other small volume Phospo-Soda disposable enema units actually contain Monobasic Sodium Phosphate, which is totally different from a standard table salt or Sea Salt solution in pure water.
Many people find Phospo-Soda enemas to be irritating and cramping, whereas a warm gentle Sea Salt or non-iodized table salt larger volume enema with an enema bag and prepared with filtered or warmed bottled water, can be soothing and relaxing to the colon.
Use one teaspoon of sea or table salt for each pint of water at 103 degrees F at preparation time, or 4 teaspoons for a full bag.