Overflow drain for an aquaponics fish tank (Hybrid aquaponic system)

In this video I show you how to build an overflow drain for an aquaponics system. This is on my 300 gallon fish tank. The water flow from my pump was to strong, so in order to have it up and running I installed an overflow drain.

Uni-seal hole size chart
http://www.unisealshop.com/page.cfm?page=3
or
https://www.tank-depot.com/shopping/uniseal-instructions.aspx