I am about to start dosing vinegar in my sump. I don't have a fuge, just 2 compartments in a 20g sump. 1st section has the drain, skimmer and a bag of Chemi-pure elite. 2nd section is the return. Would the best location for dosing vinegar be in the 1st section just upstream of the gfo/gac? Hopefully the bacteria will grow on the GAC. I have read that Randy has his vinegar dose just upstream of his GAC.