A colema is basically a very large enema...enema uses 2 quarts, colema generally uses 5 gallons. Colonics, colemas and enemas only address the colon...in part or whole. The ileocecal valve is a little door between the small and large intestines and it generally prevents anything from flowing backwards into the small intestines. A colonic....or series of colonics is needed to reach the entire 5' length of the colon. colonics provide a couple of benefits...removing any loosened waste from the colon, rehydrating the colon which in turn assists with overall hydration status, and provides a gentle internal resistance exercise that helps strengthen the bowel tone and improve peristalsis. An oral enema...salt flush...will clear out the entire digestive tract...BUT...they work by pulling water into the intestines in order to dilute the salt and the colon rapidly expels it. Rather than helping rehydrate you, they can contribute to dehydration... and can also cause a disruption in electrolytes, and they don't do anything to strengthen the bowel muscle.

Here's more information from one of my previous posts...

The primary difference between an enema and a colonic is the amount of water used...when I perform a colonic I generally use between 15-20 gallons of water!  There is another difference, though, that is much harder to describe in words.  A closed-system colonic involves the insertion of a speculum that passes and opens the second anal sphincter (an open-system uses a thin rectal tube which does not do this) so that waste flows out without any need for pushing...not straining, but the usual pressure exerted to eliminate.  This allows for a 'dancing' or 'rocking' to occur between filling and releasing...like I said, it's hard to explain it...LOL...more of a feeling for it through experience.  Rather than fill-fill-fill then release-release-release like an enema...it's more like fill-release-fill-release-fill-release as a continuous process.  This adds to the effectiveness of the cleansing process and also provides the 'exercise' to the bowel muscle... which you don't get from an enema...regardless of the quantity of water.

*Phew*...words can be so limiting sometimes...LOL...this probably makes NO sense...but it's the best I can do to describe it!  

All that being said... you have to be practical and work with whatever is available to you.  A super enema would certainly help to clear you out.  You should be using purified or distilled water for any enemas or colonics.  Either one is only going to clear what is loosened already...and only address the colon...part or whole.  Neither a colonic or an enema is a replacement for a colon cleanse, though...which addresses the entire digestive tract and not just the colon.