Cut slit in back of acrylic tank for external overflow?

[twahl]

I'm looking to get back into the hobby and I am going to be buying a tank in the next month or so. I've been doing a bit of reading and I've decided I want to go with an external coast to coast overflow off the back of an acrylic tank. I'm looking to get a 36x18x30 high tank, and I'll fabricate my own overflow. I'm wondering if I could cut a 1 inch wide slit about an inch below the rim for a weir. Originally I was thinking of cutting a 24 inch slit, but I think that there might be structural issues doing that. Now I'm thinking of cutting two slits maybe 10 inches wide leaving a 2 to 4 inch piece in the middle to carry the load through from the bracing above. Does this sound like it would work or am I missing something? Any help would be appreciated. Thanks

 

[laverda]

I wanted to do the same thing. A new custom tank was not in my budget. I would probably do three 6" slots with 3-4" between them. You could overlap another peice of acrylic on the outside to increase rigity. Also the external box will help too.

 

[mcgyvr]

Without (at the very least) seeing a picture of said tank we can only make total guesses/gut reactions..
What you are describing can certainly work just fine in some situations and may be a potential problem in another..
If you want us to fall to one side of the fence or the other I will fall on that "should be just fine" side based on what you have described so far and the mental picture I have made in my head

 

[Daddi0]

For what it is worth, I was always taught to make round corners and smooth/finish the cut outs to prevent future cracking.
Cheers! Mark

 

[john08007]

Instead of making a horizontal cut i would think a jig could be fabricated to make a lot of 1" tall 1/4" wide vertical cuts giving you the wier you are looking for, i would also think this.is less likely to clog and be more structurally strong

 

[FamilyTank]

Seems like it should work. Maybe a series of 1/2" holes?

 

[theatrus]

If the tank is eurobraced, then don't do that. If its rimless, you can, but there will be significant bowing difference between the bottom and top.

 

[1234]

If it were me , I'd make a box for the internal overflow and just put in some holes for the BH's, his way no compromise to the tank.

 

[sfsuphysics]

So I did this some years back with a 180G 4' x 3' x 2' tank, and this wasn't very thick acrylic either... think it was a TruVu tank and you know those guys totally skimp on acrylic thickness. But put the tank on the front and took a circular saw along the whole thing. My thinking at the time was that the external box is going to be welded to the back along effectively the entire length of the tank and this would supplement the lost strength due to the cut (yeah it had an obnoxiously large eurobrace, but again thin). I don't go exactly to the edge, but the slit was a good 3 feet wide. It worked fine and if I were to do it again I'd use thicker acrylic for the external box.