It is better not to elevate the sump pump to let the water flow freely. Try to change the two feet pipe to be more effective. I hope it is fixed by now.
Drilling a hole towards the top is a good idea provided that it is not made from glass. The most important thing is to prevent any overflow after the installation of the pipe inside the tank. Anyway, you did a good job also I like the flowery design of your walls, they complement the tank...