Yes Groestl algo i have no problem.
Skein algo tested on suprnova, miningpoolhub and now zpool have all the same problems : hashrate betwenn -30% and -10%. Average on 12h on any of these pools is 11,8GH instead of 14GH
i think problem is the network hashrate on the g28 configurations web page can view the hashrate is 14GH with skein algo and the orther with the same with specifications