Thanks. So 3 1/2 was too shallow for flip turns or why do you like 4 better? How deep is yours in the middle and what should I consider about that? Thanks again! Is 4.2 4.6 or 5 better or does it matter that much. If I go 5 it will add a few hundred dollars. Don't know if it's worth it or if it's TOTALLY worth it. Again, it's basically for laps but it's fun sometimes just to dip down! Thoughts?