It has a wall that is an inch tall from the inside floor but my pacman was having a time trying to get out. His big mouth kept him from being able to step on the the ledge and climb out. Adding the pieces of slate gave him enough height and traction to climb out with ease.
I have a Flucker's Pool and I just compared it to my pacman. It would have worked when he was smaller like your but now he would pretty much fill it up so maybe its not the best option. They really do grow fast and I don't think I feed mine as much as many people so mine is probably a bit smaller than he could be.
I feed mine night crawlers from Academy(not the glow in the dark ones) that I dust. He usually gets 2 or 3, depending on their size, every few days. Then every couple of weeks he gets a pink or two.
This bowl is maybe 1/4-1/2 inch deep. I threw some flat marble/stone things I have in the water dish. He can longer get more than a foot or leg wet, unless they slide.
If nothing ever changed, there would be no butterflies.