Does the 30-point rule apply to every non-manipulating move, or only to the initial move?
I am going to guess that you were most likely playing Sabra Rummikub. You almost got it right with the former. The pagat page indicates that:


  The first meld made by each player must consist of one or more combinations formed entirely from that player's hand, where the total numbers of the tiles used add up to 30 or more. If a joker is used, it counts as the number of the tile it represents.


So, for the first meld of each hand, you must meld 30 points, since the game is made up of multiple hands.