2nd attempt.. need help

so long story short. my tank was up and running for about 3 months everything was going fine until when i was at work my CPR kit siphon tube got clog and stop running water down to sump. so my custom baffels failed and broke during this time and a week later unrelated even my father did something that caused the whole house to have a brown out. so we lost power for a week. im upgrading my stand and tank to 75 gallons and i bought
Aqueon 34501 ProFlex Sump Model 2, 55-75-Gallon

for my sump, just wondering what size holes should i drill into the tank?

i also am upgrading my lights from bulbs to LEDs everything else i have i bought with this upgrade in mind.

 

look into Glass-holes.com for one of their overflow boxes. It usually comes with all the needed parts if I remember right.

 

yes, here is what I would get. Comes with everything you will need, except for the "magic lube", but you can add that for 3 bucks.

Super Nano con Dientes Overflow Box Complete Kit - Glass-Holes.com dope aquarium stuff

3/4" Inch Loc-Line Return Kit - Glass-Holes.com dope aquarium stuff

And i recommend that more expensive nano overflow kit because of its size over the others and is much easier to work with....it also has teeth, which one of the cheaper ones lacks.

 

300 gph seems low, i was thinking more like 600 to 900? or am i just wrong?

 

thats a matter of opinion I guess, and I missed the part about going to a 75 gallon display. Here

Aquarium overflow box 700gph

 

I would go as large as you can cause heaving a large overflow does hurt you, but having an undersized overflow could lead to water on the floor situations

 

Go as big as you can 1 1/2 drain. 1/2 or 3/4 inch return. The bigger drain should make less noise. And you can get more flow out of it, but you don't have to run it at max.

Edit on each side of the tank if you can.

 

...... are you sure you CAN drill your tank? whats youre live stock?