I'm puzzled.. When I look up a parts breakdown for the C 7030, this appears to be an inlet pipe, not output pipe. Also when I look at pics of the actual pipe, it appears to be a one piece pipe not what you seem to have. So maybe I'm looking at the wrong filter, or maybe the pipe you have is a homemade POS...
Is this a new pool? Where did the filter come from? Who installed it?
At first glance, as the inlet pipe, I can't see where the hole would make any difference at all. Are you having a filter issue or just cleaning it?
Something is just not right...
Jim R.