If you think its bothering the fish, you can cut out the middle of a 20 oz soda bottle and put it around the output. Here is the link
to the pictures, so you'll see what I'm talking about. If you cut out the whole middle part, it should fit on the AC70. I did that for my AC20 because my betta was getting sent into a whirlpool.
I also have an AC70 on my 55g and the only time I had a problem was when I added my cannister filter (too much current between the 2 of them). I stuck a sponge in front of the output so it wouldn't be too much.