I read the quote you placed above as the skimmer is good in sps dominated tanks up to 26 gallons. But were to to run softies you can go up to fifty.

I don't know anything about this particular skimmer, but judging the way others pursue this hobby you might want to consider yourself a larger aquarium owner in training and buy accordingly. That way if you ever get into a 55 down the road and want a sps dominated tank you won't have to worry about picking up another skimmer.

Bottom line though, this skimmer seems good to run the course in both your current ten and future 20.