Tiger barbs and cichlids in the same tank, now thats something i definitely wouldnt recommend. Might be OKish now but when the cichlids mature all hell is going to brake lose. Im sorry but you also have way to many fish in that tank bootleg. 30 barbs would of stocked/overstocked a 55, Barbs grow 3inches long. People who over stock, over filtrate to compensate but im affraid a 70gallon filter in a 55 is also very inadequate.
The idea is to choose a filter than can turn over the tank 4-10 times an hour depending on the fish. For example for a 55 wants a filter that can pump 220gph gallons per hour at the very minimum for cichlids. 55 x 4 = 220gph. My eheim 2217 'says' its rated for upto 160gallons. But pumps 264gph, Ive bought 2 for a 65. 2 x 264 = 528gph so 528 ÷ 65g = 8.1 so thats 8x turnover.
My filter does 400 gallons per hour.
400/55=7.27 times per hour.................