Bung-holes sizes for tanks

[jt41time]

I have a hex 60gal tank. It has 2 holes. One hole on top and one at bottom. The one at top is 1 5/8" and the 1 1/8" at bottom. The bungs i got from the LFS, they both have 1/2" FPT threads. They seem small. I have a major flow prob. I have seen a couple tanks with the same size hole or close to the same with a huge opening... Just bought a cpr sump that is pretty much useless if i cant get the flow i need. What are the normal sized pipe for a a 1 1/8" and 1 5/8" hole? I really don't want to drill more holes nor use a overflow setup....

 

[Ben1]

The 1 1/8" is for a standard sch 40 1/2" bulkhead,

Is the other hole really 1 5/8 or is is possibly 1 3/4" if 1 3/4" it will fit a 1" bulkhead. If its 1 5/8 its for a Sch 80 3/4" bulkhead like this one,

http://www.marinedepot.com/Standard_Thr ... 22-vi.html

 

[jt41time]

Ya it is 1 5/8. And it still has a 1/2" thread on the back. So am I screwed when it comes to the bottom one? My goal is to use the flex fose 1" on inlet and outlet. I can change the top one very easy just with a water change. Lower the water about an inch and bam.... But the lower one is about 4 inches from the bottom of tank. I would rather not drill the hole bigger... I really dont wanna do an overflow... Any sugestions?