Patients randomized to the Polyethylene Glycol (PEG) group will be instructed to ingest 2L of bowel preparation the night before their colonoscopy (starting at 7PM), as well as 1.5-2L of carbohydrate-electrolyte rehydration solution. The following day they will be instructed to ingest the remaining 2L of bowel preparation and must finish ingesting the entire preparation at least 4 hours prior to the scheduled colonoscopy.

Patients randomized to the Picosalax (P/MC) group will be instructed to mix one sachet in 150mL of water and ingest the entire mixture at 7PM the night before their colonoscopy. In addition, they will be instructed to ingest 1.5-2L of carbohydrate-electrolyte rehydration solution after they consume the P/MC sachet. The following day they will mix the second sachet in 150mL of water and must finish ingesting the entire preparation at least 4 hours prior to the scheduled colonoscopy. They will also be instructed to drink additional carbohydrate-electrolyte rehydration solution after they ingest the P/MC sachet.

Patients will be asked to complete a questionnaire to assess ease of completion and symptoms. Questionnaire items are weighted on a 5-point Likert scale. Interference with sleep will be assessed through a questionnaire that is based on a modified validated sleep questionnaire (St. Mary's Hospital Sleep Questionnaire). Participants will be asked to complete this questionnaire at the initial appointment and again on the day of their procedure

The colonoscopist will be blinded to the type of preparation the subject underwent. The colonoscopist will complete a validated questionnaire to assess the quality of the preparation (The Ottawa Scale) and the 4-point Aronchick bowel cleansing scale. The patient's baseline bowel habit will be recorded, as well as the withdrawal time, volume of liquid suctioned and volume of washing fluid used during the colonoscopy.