I have read several post were people add the CO2 into the intake of the
canister filter instead of using a diffuser. I have just added an Eheim
2215 with a surface extractor. Would adding the CO2 to the intake have any
real advantage over the Hagen diffuser I am presently using. It is the
diffuser sold with the natural CO2 system, but I am using it with a 5lb
bottle.

What is the best way to do this? Should I drill a hole in the intake and
route the hose it there? If I did this I think it would be difficult to
see/count the bubbles.

If I anchored the hose below the intake I could count the bubbles, but they
may not reliably get sucked into the filter.

Any advice is appreciated.
Scott