When I swapped out my mag5 for the mag9.5, it overran the AGA overflow unless it was throttled back.......
BTW, do NOT take this as an endorsement for a mag pump.
If I was doing a submersible, I would do an eheim if you have the $$$, or an ocean runner if you don't.
My mag5 pump is noisy, and adds a lot of heat to the tank. I'm just not doing another pump purchase if I can avoid it.
A little empirical data on how much heat a mag pump adds:
My 43 gallon brute trash barrel was full of water measured at 69 degrees. (which was room temp)
I brought that barrel up into the first floor of my house, which was AC controlled at 75 degrees. I put the mag 9.5 pump in to circulate and aerate the water. The next day (12 hours later), the water in the barrel had gone from 76 to 84 degrees.......