Does my tank have good filtration?

i have a 55 gallon tank. it is 48 inches long. i have 1 HOB 30-60 gallon filter, 1 20-30 gallon HOB filter (both on opposite sides) and 1 under the gravel filter that is sort of in between them both. is this good filtration or do i need more. i have no power head, do i need to get one in there or not?