Thanks for the quick reply.

The 3 locations noted are similar to what was recommended by a local sales rep that recently came out and did a consultation.

Prior to his visit, I was assuming I would just need two. That said, I am wondering if a third diffuser would be at all worthwhile considering that I am more focussed on keeping the pond low maintenance & clean for swimming. I want a nice fishing pond, but not at the expense of the other two goals. Or would it not make a difference?

As for the tubing, I wasn't planning to use weighted stuff outside the water, but the guy I had out said (if they installed it), they would run all 3 unweighted lines out together and enclose them inside some sort of PVC conduit to protect them from digging, etc. Then, the 3 unweighted lines would be fitted to the weighted stuff at the shore. For whatever its worth, I will have to trench the entire 300' run through hard-packed clay (spoils from the pond dig). With that in mind, I obviously want to make sure that tubing is as safe & secure as possible because I will not want to dig it up for repairs or replacement.

Would a single tube to the shore be cheaper or "better" in any way than 3 unweighted lines?