What is it about the HOT Magnum that meets your criteria?

Thanks.

Heavy emphasis on the "if" part of my original statement. IF it had a
connection point for CO2.

as to how I envisioned that it might fit the criteria....

-it hangs on the tank like a power filter...for the applications I
have in mind I dont have space for an outboard canister.

-if CO2 could be introduced pre-impeller the entire internal part of
the filter is more or less as a reaction chamber. using the internal
canister instead of the micron cartridge you could put some kind of
bubble chopping bio media into the canister.

-it's leak proof such that once the CO2 is introduced it isn't free to
escape like a normal power filter

-the water return can be directed below the surface as opposed to
normal power filters which simply spill over the edge therefore less
CO2 loss.

I'm pondering using one of these for a new 30 gal tank on an unused
stretch of kitchen counter where only a "hang on" type of filter will
work...and bubbling the CO2 into the intake.