Bruce, IMO what you are doing with the conical bottom makes all the sense in the world.
I currently have an aquarium with pellet trained WE in it. I wish the bottom was conical, and had a drain in it, as it would save me from siphoning debris from the bottom and hauling buckets of water to the aquarium a few times a week.
Go with your hunch, and dont let others cause you to second guess yourself!
You did not become "MR. BLUGILL" from listening to people say "That wont work"!
My only input, is if you do buy the taller tank with the screw off lid and you cut the top off of it, I would use strapping of sorts around the tank to stabilize rigidity.
Popping popcorn and watching closely!
I just re=read what Esshup said about cutting the top....THUMBS UP!
You're right...siphoning is a huge pain in the butt. Often it will freak out the fish, which in turn resuspends the semi-buoyant solids--defeating the purpose. Very inefficient and labor intensive. I know exactly what you mean. Currently in my cubic tank, I'm siphoning on a daily basis. My biggest enemy is fish-spooking. My second biggest enemy is that in a tank that big, I have to roll up my sleeves because they get wet each time.
I laughed at the popping popcorn metaphor. I'm hoping to avoid a bowl full of old maids.
Holding a redear sunfish is like running with scissors.
