Some people find that taking enemas too frequently can cause them to become "addicted" and unable to have a bowel movement naturally. I'd advise you to try the weekly enemas for no longer than 6 weeks, then try and go a month or so without.
Personally, I love enemas, so I tend to have an "enema day" once a month, when I dedicate a whole Saturday to cleansing. I think that in this way I avoid becoming dependent on enemas but at the same time don't get constipated and can enjoy the benefits of having a clean colon.