I still want to try this, just to see how it works. I have delved into this so deeply now, I am just curious to see what happens, hell I am retired and this little ( but expensive ) test will give something to do and might just be informative for the other members here, lord knows I get ALOT of good advice here, I just might be able to give back here, who knows, might just save somebody a little time and money…..
Sounds good to me. I am a strong believer in experimentation to solve complex problems, so I like your attitude!
I do not think the fluid flow will be much affected by your deep pipe, if you go with a large diameter.
However, it might mess up the buoyancy of your fountain a little. PVC pipe is only 39% more dense than fresh water. If you use heavier pipe, I still think you can easily add a pipe strap near the top with an underwater clorox jug to get back to the fountains design float level.
Good luck on your project!
P.S. Have your brought your wife in on the design phase? I have discovered that act scores me some additional points in the "good husband" column AND I don't have to revise things later since the project was approved at the highest level!