Following negotiations with Cardiff City Council, Cardiff Blues can confirm that this Friday's match will also be played there but with capacity being raised to 9,000.
Speaking of the announcement, Cardiff Blues CEO Richard Holland said:
"Firstly I would like to thank all the staff at Cardiff Arms Park and the Cardiff City Stadium for working tirelessly to make sure that match could be played at Cardiff Arms Park."
"I would also like to thank all the supporters for turning up on the evening which was a great occasion and a great result both on and off the pitch."
"The supporters seemed to enjoy being back there and following negotiations with Cardiff City Council I am delighted to announce that we have raised capacity for this Friday's match at the Arms Park to 9,000."
"As I said on Friday night, there are no long term plans in place to move back to the Arms Park permanently."
"We still have a 20 year lease in place at the Cardiff City Stadium and playing these two fixtures at the Arms Park has no impact on this agreement."
"However, some games are more suited than others to be played away from the Cardiff City Stadium and this is something we will be looking at going forward."
"We have arranged a Board meeting for Friday to discus the rest of the season and will be reviewing the situation for the 2012/13 season also."
All season tickets holders, premier club members and supporters who have purchased tickets for the Ulster do not need to take any action as their tickets are valid for the game.
Tickets for the match will go on sale at the Arms Park Ticket Office, (opposite Angel Hotel), Cardiff City Stadium Ticket Office, online at www.cardiffblues.com/tickets or by calling the ticket office on 0845 345 1400