adding holes to a perfecto corner overflow

so, i want to set up a 90 gallon. think i have decided on a marineland 90 gallon with corner overflow. the LFS is going to add one more hole in the overflow so i can do a herbie style overflow and still run the return inside the overflow.

how much room is in the bottom of the tank in that overflow??? anyone see a problem adding a hole that close to the other 2 holes?? what about a 4th???? maybe ill just ask if i get the added hole large enough for a 1.5 in bulkhead so i can use the 1in as the emergency. i just dont wish i had more flow through the sump at some point.

 

Normally the bottoms of tanks are tempered glass and drilling is a no no. factory holes are usually drilled before the tempering process.
I would make the LFS guarantee their work before allowing them to drill. I may be wrong on Perfecto but most others are tempered on anything above 55G.

 

I completely agree, never have anyone do anything for you without a guarantee of some sort. You don't want them ruining your tank and saying Tough luck.

 

the bottom of the tank is not tempered, and the LFS will back up the drilling.
http://www.marineland.com/sites/Marineland/Documents/Corner-flo Tank Specs.pdf

my concern is that there is not enough room for an extra hole in the corner, or that a hole in proximity to the other two holes will weaken that corner to the point it may break later.

 

what I would do is instead drill it in the back of the tank still within the overflow box. And just use that as your emergency overflow. I used my original return for my emergency overflows and then ran my new returns up and over the back of the tank.

 

yeah i thought about that a lot. only problem is that my "reason" that i give my girlfriend for getting the 90 is that it wont be any bigger then my 55. just will be up against the wall. i have HOB stuff with my 55 so the jump to 18 inches deep with no HOB will equal out.

kinda ling explanation for............i want to put the tank against the wall so not sure if i can run the return between the tank and the wall