Fish tank water flow problem

Agree with the first floor, according to you, your original 2000L/H can reach the water balance, that is to say, the amount of water leaking down the water is also, now add a 2000L/H in the top, that is, the amount of water leaking is two 2000L/H, the bottom of the pumping also need to double just to reach the balance of the water cycle, that is, 4000L/H.

But I do not quite understand the design of the owner's tank, why is the bottom leakage of water, why is the bottom of the tank? Why do you need to leak water at the bottom, what if the power goes out? Won't it leak the water to play? Or the pump that pumps the water for a long time with low performance, that is not the tank will leak all the water?

I think it's much safer to plug the bottom leak and pump up. (Personal opinion)