But even with a reactor, there is a pressure drop like with this, it's just smaller and easier to make.

A nice venturi would be a good CO2 device though, it would get the disc out of the tank and do the same type of thing.

Reactors are designed to get the CO2 100% dissolved, disc sort of do that unless you blast the bubbles around.

Why have a disc and a filter doing this when a venturi in line with the filter can?

Regards,
Tom Barr