I was hoping the 2x8 would be strong enough, and according to calculations it should support the weight since they are 12" on center. I agree though I would rather have overkill protection. I may add some extra 2x8 about 3.5 ft in so that I will have 2 spans (1 @4.5ft the other 3.5ft) I need room to get the 4ft sump out.