Fine , you don't have to use my idea of two powerheads , see if I care! lol !
I know what you mean ,thats what is so nice about biocubes everything is hidden!
What concerned me is sometimes the water in the pump chamber gets pretty low even with the stock pump. So you might have to mod the chambers so it does not drain too quickly with the more powerful pump!
Let me know wht you do because i would like to get my second PH out of the tank.
I do have to tell ya though, the new Aquaclear 301 that I just put in looks pretty unobtrusive compared to the MJ400 i had.
good luck!