Bro go for a 3ft width. You will never regret as with 2.5 after you placed the LRs in the center, you'll find that you'll be left with little sand bed area to put corals. And also put you tap near the sump where you can tap it to a DI unit for auto top-up. Me did it all wrong where now my tap is still at the top of my tank very difficult to modify liao