Well it depends on what species of coral you are keeping. If the tank is going to not house coral a turnover rate of 10-15x is sufficient. However if you do keep coral you will want more water movement. Two model 20's(126gph each) should be more than enough in my opinion for a 10g housing Softies and LPS. AquaClear powerheads have a large profile especially for a 10g so you might want to look into Microjets or Minijets which are much smaller.
What are you planning on keeping in this tank?