K...These 3 sumps will give you a 12 inch water level regardless of the height of the middle baffle. Also, once the 1st or 3rd baffle is set to 12 inches and neither one is any higher than 12, then water level will be set at 12 inches where you want it, but if one goes any higher than 12, then your water level will be set to the height of the highest baffle. So you can cut all of the baffles at 12 if you wanted and will be fine... Even the middle one. Just make sure you leave atleast a 1 inch gap at the bottom of the middle baffle to allow water to pass under without any issues