I have a 10gallon-Tall in my kitchen/dining room for my Betta (12 x12 base, 19"tall). I feel like the HOB is just stupid for this tank as the bottom doesn't get filtration without modifications where you might as well use a sponge. Given that the footprint is more limited, and I want a taller column or greater vertical space of gentle water movement/filtration (for Mr Betta), it makes more sense to me to stack skinnier sponges. (Will end up looking like the sponge on the intake tube of my HOB without the need to prime my noisy, too violent for a Betta, floating-plant-eater HOB.) Wish I had a second tank like this to run experiments with sponge filters and dye, but then I'd probably just buy another Betta and neon tetras (my minions)! I absolutely love this tank as it's just as much joy as 2 small, stacked tanks. Looking for better-suited filtration for it. Love the idea of having two cycled sponges available for hospital visits without giving up aquarium floor space. (1) Would also love more ideas on stacking. (2) Would also like more visual demonstrations on using a powerhead to keep noise to a minimum in "conversation areas" of the home. (3) Would love ideas/solutions for minimizing excessive water flow for a Betta tank without loosing too much filtration...WITH a stacked sponge and powerhead (anyone have a 3D printer for a fancy, yet pretty tube?). Hope I'm not asking too much! ...A girl can wish.