Biocube Sump Connection

I have a biocube 29 that has been running for a year now. I just set up a small frag tank with an overflow that flows into a 10g sump and back. I also want to connect my biocube to the same sump to have both tanks on the same system. How would i do so... Where do i drill... what pipes... which chamber do i drill (1st, 2nd, or 3rd)...
btw i am NOT using a HOB overflow
Thanks

 

Hey, check out my build thread. There are some detailed pics of the overflow I made. Also you can check out Mobilized build thread too.

I'd post a link but I'm on my phone.

 

when you get a chance can you post a link, i cant find it. Thanks

 

http://www.3reef.com/forums/show-off-your-fish-tanks/biocubes-build-thread-weather-added-133894.html

 

Here you go

http://www.3reef.com/forums/show-off-your-fish-tanks/biocubes-build-thread-weather-added-133894.html

 

Thanks guys

 

I saw the overflow you made on the forum post. I looked at it many times but am confused about how yours works. Is it a siphon or just an overflow? And if it is a siphon, how do you get the return pump to match its speed?
Thanks again

 

Here, this might help. There are a lot more pics on how I made it and installed.

http://www.3reef.com/forums/refugium/mini-fuge-biocube-diy-thread-w-pics-129422.html

I am honestly not sure how to answer your qestion about it being a siphon but since I used 1in pipe I can push up to 500gph (if wanted) and the overflow doesn't bat an eye.

 

WOW, thanks so much, i saw your comment... "The overflow will start back up when the pump turns on. Also there is a 3/4 check valve installed right off the return pump."
I would have never thought it would just startup again because of its shape.
Thanks!