Acrylic overflow box to glass

Buell 1125cr · Jan 31, 2015

Paul B just had an interesting read on rumors and got me thinking. I am just getting back into a build I haven't worked on in about a year and was getting ready to cut this acrylic overflow box out of my tank because it is held on with silicone and replace it with a four sided one that would be held on by the bulk heads. I did a search and came across a few back and forth threads which is probably where I read it before. So I guess before I spend $100 on a new overflow is there any one with long term success with an acrylic overflow box held on by silicone to a glass tank. Or anyone who has had a failure. Preferably on A large tank because I think it would be under a little more stress than say a 10 gallon. This is what I am currently working with.

kschweer · Jan 31, 2015

I have seen threads go back and forth over whether or not silicone is good for holding acrylic to glass, with most people saying it it not. I will preface this with saying I have no hands on experience with this just my observations. Any off the shelf stock tank has the acrylic overflow box siliconed in place. All that I have used and all that I have seen have held up well. Now those are full length boxes with some of the weight being held by touching the bottom glass. In my opinion if it's a good silicone job and the glass was clean before siliconing I think it should hold.

On another note, if you would feel better having the bulkheads holding the box you should be able to cut out the box that is on there and simply "weld" a back panel in that is drilled for the bulkheads instead of buying a whole new box. Should be fairly easy to do and much cheaper than buying a whole new box.

redfishbluefish · Jan 31, 2015

I would imagine that that overflow is a bit noisy. Have you looked at Glass-Holes? They make a nice and relative small acrylic overflow box that is four sided, and at your size, held in place with two bulkheads. And FYI, there is a gasket between the overflow and the glass of the tank. The inside of the overflow is baffled, so virtually no noise.

Here is the 1500 gph overflow (inside tank)

And here's the back side of the tank:

Buell 1125cr · Jan 31, 2015

My plain was to run one of the drains with a 90 degree elbow upside down and run a full siphon with the other being right side up as an emergency. It should be very quite. That's why I didn't want a low profile box.