Greg, you say:
You "backed out"? I tried to set you up on that build and you BLEW IT. Instead of sticking to the proposal as submitted you attempted to "sell him" on your methods. The owner felt more comfortable with someone who actually knew Koi and ponds instead of "make shift" and "jury rigged" construction techniques more typical of DIY watergardens from a paperback guide.
If he has a problems with the "system", I am sure that the contractor involved will rectify the problem, he is reputable. Noticed, I did NOT assume it was a pump problem. Unlike many, I withhold my opinions until such time as I can base it on factual evidence, you see, "sucking air" can be the result of many different factors, not just a fault in a pump. That is the difference between you and I Greg, knowledge and experience.
Steve Childers