will this cause a flood.

[kj-1]

i agree with the stand pipethere are several ways to modify your overflow and/or the stand pipe to work in almost any overflow. i am getting ready to set up a new 100g with an internal corner overflow, it is only 5 inches square and i modified the the stand pipe to work without using smaller PVC. you can do it in your external overflow also. you can seal the bottom of your overflow box an drill into its side and follow the instructions at richard duraso's site listed on the previous posts. i've been in the hobby for around 7 years with several DIYs under my belt but i never thought about the stand pipe or converting it to an external overflow. it would be your best bet.