The hole has been dug and I am quickly regretting my depth choice. 20 x 40 rectangular with 6 ft tanning deck - 3 foot depth for 10 feet - transition to 3.5 foot for 10 feet and a slope to five foot. I have a 7 and 12 year old - hoping for volleyball in the shallow and a slide will dump into the 5 foot section. Is this too shallow in the 3 to 3.5 range - does 3.5 to 4 make more sense?