I'm planning on an external overflow for a glass tank with the back glass of the tank cut down for the weir (no bulkheads for attaching the external overflow to the tank). I understand that attaching glass to glass using silicon will give a strong bond, but I'd like to have some kind of background between the overflow and the back of the tank (likely a large vinyl sticker, like contact paper). How could I attach the overflow box to that? I want the box invisible from inside the tank, so you only see the background. I'd really appreciate any ideas!
Attaching an external overflow
- Thread starter Leanan
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uncleof6
Active member
mfinn
Active member
It is a very unwise move to use acrylic for an external overflow box...
Didn't mean to sound like I used a external overflow box. These were internal boxes.
I only mentioned them because I used the same colored acrylic on them as I did the sheet across the inside back of the tank.
Gave it a seamless look with the same color.
It is a very unwise move to use acrylic for an external overflow box...
Why is it unwise?
Ok that's what I suspected but I was hopeful I could make it work; thanks for the info!
My next thought is to attach a piece of colored acrylic (or glass I guess?) inside the tank - could I do that, and just silcone the edges all the way around? Would it stay in place?
Because silicone does not adhere to acrylic very well and there for not recommended to use for external overflow
mfinn
Active member
You could absolutely do that. Remember, though, that acrylic will warp in the presence of water (on one side but not the other) so just using silicone around the edge may be insufficient.
mfinn
Active member
There was no warping in 8 years on my tank.
When the tank was drained and cleaned for moving, the acrylic had a few scratches on it from 8 years of use. Other than that it was pretty much the same as when I put it in.
I did put a few lines of silicone in the body of each piece as well as around the edges.
Awesome, that might be the plan then.
One last idea - could I put the vinyl inside the tank, then put a piece of glass in front of it and silcone in place (like I would with the acrylic)? Just curious because I liked the idea of a vinyl sticker printed to fade from light blue to dark blue, and glass in front of it would be less likely to get scratched up than acrylic (I'm planning to keep the back of the tank clean of coralline). Thanks!
mfinn
Active member
If I wanted to do this, I would want to put a few lines of silicone in the field of the glass to help hold it. But if you do that, it would show through the glass.
Plus if you use a piece of glass, you would have the added cost of matching the cutout to the back wall of the tank.
My tank maker used a solid black vinyl on the outside of the tank around the external overflow box, and on the inside of the overflow box facing the front.
He also used black silicone to hold the overflow box on the tank wall.
The only time you really notice anything is when the lights are out.
Which is why you didn't get warping. OP states he is going to put silicone just around the edges - not the same thing!
This is going to be for just a 50 gallon tank (24x24x20) do you think the acrylic warping would still be an issue?
Also, if I used a pane of glass instead of acrylic, could that just be siliconed in around the edges safely with no warping? Thanks so much for your help! Just trying to find a compromise between aesthetics and practicality
mfinn
Active member
This is going to be for just a 50 gallon tank (24x24x20) do you think the acrylic warping would still be an issue?
Also, if I used a pane of glass instead of acrylic, could that just be siliconed in around the edges safely with no warping? Thanks so much for your help! Just trying to find a compromise between aesthetics and practicality
Glass does not warp, but it will be more difficult to cut the sections you need. If you go with acrylic, use as thin as possible and pit some silicone in the middle which should stop it from warping. Acrylic absorbs water, so if one side is exposed and the other is not it warps unless you hold it flat.
Thanks again for the help. When you say "as thin as possible" you are referring to the acrylic sheet, correct? Wouldn't a thicker sheet have less tendency to warp? Or, would a thicker sheet warp with more force and be more likely to pull itself off the back of the tank?
uncleof6
Active member
Becasue the acrylic will not bond to the glass using silicone...I doubt anyone really wants their overflow falling off the back of the tank, so it is not a very wise thing to do...
