I doubt your pH of 7.9 reading. Also, you might want to drip a little Kalkwasser in the evenings to better raise alkalinity and pH semi-quickly. The free hydroxides will also help precipitate phosphates, actually increasing your skimmers performance, along with other benefits. Just don't overdo it, and don't try to use it to "raise" your calcium levels, there are better ways for that. As far as Super dKH buffer, I have used it in the past and found it took an awful lot to do any permanent good. Anyway, that is just my 2 (maybe 3) cents worth...