Depends on the type of cichlid. Malawi cichlids are not suited to 29g, as they need very heigh stocking levels to prevent your 10 fish becomming one....
Dwarf cichlids can be stocked to one pair to every 10g, providing there is enough cover for both pairs to get away from each other.
I'm unsure of tanganicas stocking density, so can't realy comment here.
I belive powder blue cichlids are malawis? Could you post a pic of these and the other fish you have, and then we can ID them for you and give more info

to TFF
Rabbut