I’m not sure what to tell you. I’m not familiar with a red sea 250 and the dimensions. But I would just say it’s a trial and error type thing. When I started my 150g I thought for sure 2 MP40QD on the back wall and a m1 on close loopon was going to be plenty of flow. I wasn’t happy tho. So I added a mp10. I still wasn’t happy so I sold 1 MP40QD and bought 2 Nero5s. I then had 1 MP40QD on the left side a mp10 on the right, 2 Nero5s on the back wall, and the m1 on reefcrest closeloop. The flow was great. But I then got sick of seeing 2 pumps on the sides of the tank. I started thinking why do I have a 3 sided starfire tank and I’m blocking the view with pumps. So I ditched the side vortechs and went with seaswrils on the closeloop m1 on reefcrest mode. Now I’m running a mp10 and 2 Nero5s on the back wall and the seaswirls closeloop and I love the flow. My flow patterns are always changing. I’d like to credit that to the seaswirls running on reefcrest. I’m I do anything else I’ll ditch the mp10 and go one more seaswirl in the middle
I suggest to just try things out. Every tank is different. Your rock structure will play a large part in dead spots.