At first glance the filter looks like a great setup but I think it could be a lot more efficient.
In the side portion, you have 4 eggcrates levels. Remove the bottom piece of eggcrate and put it under the bio-balls to keep all of them up out of the water. As it is now, almost half of them are underwater. You'll then have 3 filter pad drip trays and 1 fully usabale bio-ball chamber.
On this part, only that top chamber is properly doing what it's supposed to. Well that's if the water coming out of the top tube is it being evenly distributed onto the balls. I can't tell if it's just pouring into the center of them or not.
On the bottom level you have to find a way to lower the water level so the balls aren't all submerged. You could rig your pump outside of the sump and run a hose either the side or over the side. Either way, you could lower the water level about halfway down by having the hose all the way against the bottom of the sump.
When you do water changes, if you add tap water straight to the tank, make sure your pump isn't pumping water thru your media until it's been thoroughly conditioned with Prime or equivalant. Sorry I'm sure you know that.
On my 265, I use a 55 gallon wet/dry that has two individual large bio ball chambers slightly raised to keep them out of the water. It runs 1800gph wihich is probably sufficient but I also run an FX5 and xp3 plus an Emperor 400 hob for added measure. I can't take a chance of underfiltration. GL with everything.