I did what Brendan Redler did without reading his post, for the same reason- the hole is just to small in the flow adjuster slot.
Anyways, this method seems to dissolve so much of the CO2, and the little bubbles leftover get swirled around my tank by my powerhead, so there is CO2 all over the place
However, it isn't as quiet as it is made out to be for me. It sounds the same as what it did when I had my DIY going into my HOB filter. Same bubble crunching sound every time. I'll get used to it though- the price we pay for beautiful plants