Anyone build a Hang On Overflow??

[200gal]

I am wondering if someone can give me any good ideas for building a hang on overflow. Plus what experiences they have had with them. My tank has a 3.5 inch glass brace around the top of the tank so I do not think a manufactured one will fit. Just that my tank is full and not enthused about emtying it to install an overflow. Has anyone had any success or failures with drilling near the top of a nearly full tank?

[Canadian Man]

I have some pics on my site. Click the link on the bottom of my post.
It was my first diy project with acrylic and it works great. I have my sump plummbed to the basement and have had 0 problems with the overflow. As long as you build it properly there is no risk of loosing syphon.

[200gal]

Thanks Canadian Man. Was just wondering a few things. What size are the two flow tubes and what are they made of?
What size is the drain hole and tube running to the basement? I do have the basic principles of how to build it. I was also planning to plumb to the basement also. What kind and size of pump runs your return and what size is your return line? Is the tank in your basement raised much off the floor? What size tank were you running this overflow on? And by the way, nice job. :wink:

[Canadian Man]

Thanks!

Ok here it goes.

-the flow tubes(U tubes) are about 1" ID acrylic. They are actually J tubes cause one end is longer then the other. I got them from the local Big als.
I am using three in the overflow. They are made of acrylic.

-I am using 1.5" pvc for the drain to the basement. I also added a durso stand pipe to the unit to quite it down a little.

-The return pump is a Little Giant 4mdqx-sc and the return pipe is 1.5 also up untill it reaches the tank which it then goes to 1"

- I built the tank in the basement (75g) about 3 feet off the floor cause I was scared that the pump wouldnt make it up but no problems at all. There is probably aobut 600gph with all the head and everything. I am actually thinking of lowering the sump closer to floor level.
The main tank is a 90g tank.

The one important point I will tell you about (you may all ready know) is that the height of the divider in the outside box determins the height of the water in your in tank box when the pump's are turned off. So you want the inside divider to be higher than the lowest U tube in the inside box. If it's not your syphon obviously looses it's syphon. :wink: :D

Let me know if ya got some more question and thanks again.