Ok, I my non professional opinion Id use both baffles, and silicon them in. Leave the one you have installed where it is, but raise it off the bottom one inch. Then use the second one in front of that one(to the left in your picture), and have that one touch the bottom. This will make the water go over the first baffle, and under the second one creating a bubble trap. That way you dont get micro bubbles in your display. The only problem is that the top of the second baffle(the one you left in) will have to be higher than the top of the first baffle.
The water level in the middle section will be set by the top of the baffle that touches the ground. I can make an illustration if that doesnt make sense.
No sump expert myself but that sounds like a good idea.
