Question for the beananimal overflow experts

[Werbo]

Thanks guys. In summary:

1. Main drain fully submerged with a strainer 3-4 inches below the secondary drain.
2. Secondary drain has a T fitting followed by a down turned elbow to set the height of the overflow box (2 inches below the water level of the main tank). Airline tubing (as in picture) coming out the top.
3. Emergency drain with a T fitting and an upturned elbow (to allow stop water from flowwing when your arm is in the tank). Cap the emergency drain to make it air tight?