The max output for the Aquaclear 70 is 300 gallon per hour. It's rated for 40g to 70g
http://www.marinedepot.com/filters_h..._power-ap.html
I learned from other experts before that we need flow rate 10x of your tank size. So, the Aquaclear 70 is not even enough for a 40g tank.
I am currently use an Emperor 280 for my 40g tank. That filter has a 280G flow rate and it's working very well for me. I was looking to buy more Emperor 280 until I saw this deal. I like the media option and the sales price, of course.
BTW, the more filtration, the better .. If indeed you have a 70g tank, I don't think this filter is powerful enough.