Excellent advice FishinRod! Thank you; I will get on your recommendations and post back.

Crazy thought. If I build a plug for the exit, is there any chance I can do anything by inserting my leaf blower in the end? If nothing else, maybe it tells me how far out in the pond my inlet is?

Another crazy one......I have a GoPro and a waterproof light. Thinking about rigging them both to a long cane pole and livestreaming to my phone as I follow the inlet pipe into the deep?

I am the most avid DIY'er, and not rich. I love to try to figure stuff out before I call in for help.

You all are great, and I appreciate it!
David in SC