Tank Design Help

[sphelps]

Do you need two overflows? I know it seems to be common practice to run two on larger tanks and correct me if I'm wrong, but wouldn't you get better surface skimming with one overflow? Reasoning for this is that a single overflow alone will bring in twice the water as an overflow in a dual setup. This will result in a higher water velocity on the top surface and therefore greater surface tension which to me would suggest better surface skimming.

In addition you would run your return on the opposite side to create a general flow pattern towards the overflow which should produce a more efficient turnover. Plus you have more defined upstream and downstream areas which can be beneficial when keeping different types of corals.

Single overflow boxes have been common practice for the tanks I build and I've always had good results. More cubic tanks are a little different but for the longer narrow tanks a single overflow and return on the opposite just makes sense to me.