I got some sodalime , put 500ml in a reactor in front of my skimmer air intake. The pH instantly got raised from 7.80-8.1 to 8.15-8.50 (early morning – late night values). The bad news is that it only lasted 2 days, the third day I measured lower values (8.05-8.30) and the fourth day it was totally exhausted. Doing some math, the 5L media would last about 3 (max 4) week in my case. I have 700-800 l/h air intake for my skimmer. However it is a very efficient way to raise pH, in my opinion it is not a sustainable solution in the long run (especially for larger tanks where air intake is even higher).