Must say that running a hose outside, or even using a CO2 scrubber, made very little difference to my tank's pH. I'd argue that if either of these approaches do make a material difference, gas exchange in your tank maybe poor.
In my case it is simply that my house has too high CO2 level due to its being very sealed up. Confirmed with Aeration Test as prescribed by Randy here:
Low pH: Causes and Cures by Randy Holmes-Farley - Reefkeeping.com
If low PH is due to a different cause then it is assumed this approach won't work.