BarO...

The heavy weight of the PVC on the bottom along with that diffuser acting like a parachute virtually guarantees it will land right side up. If he had used 1/2 inch pvc instead of the larger diameter, it would be far more likely to tip over. If it is warm enough, it is better to swim down and place by hand just to ensure that they don't flip over.

Water dries, rocks crumble, and trees die. The only thing that is eternal is the reputation we leave behind.
- Ancient Viking Proverb