Geo Method here also. From the first time I put water in and dumped some water in the black tank it smelled fresh. I also put it in after black tank flush. Unless the heat of the summer brings an odor this is all I will do also. And I did the "shake" test on the TP I use and it passed with flying colors.
Jim & Linda Tator
2013 Crusier CF34SS Ford F250 PSD 7.3L
Ride-Rite Airbags Bully Dog
154 nights in 2013 - 4,370 miles
128 nights in 2014 - 5,082 miles