I think so - is a 30" T8 rated at 28w? I can't seem to find that size...otherwise that ballast is rated to handle 4-24" T8 or 4-36" T8s, so I believe that it should be able to handle 4-30"ers.
75g FW Planted Community; 55g African Cichlid
29g Biocube SW Reef;12g AP Mantis Shrimp/Brittle Star
2 Cats, 2 Dogs, 5 Turtles