overflow box decided to spring a leak

[Henchman24]

My overflow box decided to spring a leak & started spraying water on the walls today. It think my upstairs neighbor's sumo wrestling maybe partially to blame but overall I can only blame my inexperience using weld-on. Weird that it made it the 110 days or so that I had this setup so far to do so. I could probably get away with just using aquarium safe silicone to seal up the crack, but I am going to add some more acrylic pieces to try to beef it up. Then add some silicone around the edges for good measure (warm fuzzy feelings)

 

[Henchman24]

I added a second piece of acrylic on the side that was leaking & added a layer of silicone all around the inside. I wonder if the fish will get High from all the fumes.

 

[brian cummings]

What type of weld-on are you using?

 

[Henchman24]

Weld on #3. I am thinking about ordering some #16 to add around the outside. At least it started leaking while I was home and not when I am going to be out of town for the fourth of July.

 

[zrogst]

To be fair, I think most overflows leak with time. It's just that most overflows are inside the tank and no one notices Glad you caught it while you were home!

 

[evolved]

Silicone doesn't really bond with acrylic; I'd suggest only using weld-on.

 

[Henchman24]

The second 1/4 " piece of acrylic I attached on the right side where it was leaking seems to be sealed nicely. not a drop of water so far. I didn't do the best job at cutting the acrylic. This was my 1st attempt at scoring & snapping acrylic.

To be fair, I think most overflows leak with time. It's just that most overflows are inside the tank and no one notices Glad you caught it while you were home!

That's why most overflows are on the inside I guess. I was thinking about getting the most tank space possible when I set this up. I might redo the overflow box on the inside at some point.

Silicone doesn't really bond with acrylic; I'd suggest only using weld-on.

I completely agree that weld on makes a better seal than silicone. I added the DAP Silicone around the inner edge just in case. The DAP aquarium safe silicone actually seems pretty solid. I ordered some Weld on #16 to add around the outside. It is thicker & supposed to be way better at sealing up leaks than the #3 or #4.

 

[brian cummings]

Did you do anything to the edge of the plex after scoring and snapping? The edges needs to be prepared, scraped/jointed/something so they're smooth and flat....otherwise you don't get a good weld..

Did assuming you just "capillary" bonded them, that generally isn't to strong, doesn't give the solvent enough "bite" into the plex... Need to use "pin method" perhaps, but would have to do that with aquarium empty and on it's side...

Weldon 16 will seal some leaks, but has a weaker bond.

You might add some little strips of plex around the outside...

 

[brian cummings]

Also, what kind of acrylic was this?

 

[Henchman24]

Brian,
I originally used cell cast acrylic pieces cut to size that I ordered to build the overflow box. I used a scrapper tool to smooth edges. I didn't use the pin method but I think I did a decent job putting the pieces together that were ordered. The weld on got sucked into the edges through capillary action & turned clear where the pieces meet. The problem area was where the overflow box which is clear acrylic got bonded to the back of the tank which is a black colored acrylic. It still has a clear seal like the rest of the seams for the most part but there are tiny bubbles in certain places. About 4 months ago when I did the first leak test there was a leak in the same spot that was leaking a few days ago. I added some weld on & thought everything was fine after the next successful leak test. I bought a 18" by 24" sheet of acrylic from home depot that I scored & snapped to add as a 2nd piece on the right which now looks half *ss. I used the flat already cut edge against the tank where it was leaking.

 

[brian cummings]

Sounds like you did it the proper way.

Cast is the way to go, but the word is not all cast is created equal. Brands/products to look for: Acrylite GP or Plexiglass G. There is another good one, but the name escapes me. Not all cast products have a polymer structure conducive to good bonding.

The pin method gives a good bite and makes a filet on the outside/inside of the edge

Don't know if you mean to say the black and clear acrylic are perhaps incompatible, but they shouldn't be, as long as they're similar cast acrylic.

And oh, I have seen plenty of overflow boxes built on the outside, not just inside.

The Home Depot acrylic is no good to make anything from, but it probably works fine as a bandaid.

Acrylic welding is an art and a science, that's why a lot of us have paid good money to have one of the pros do it-- but that's not to say that one can't or shouldn't attempt DIY... I am working on some 1" thick myself right now, hopefully I don't mess it up!

 

[Henchman24]

I leave on Monday to visit my family in Michigan for a week. I am semi confident that the repair to the overflow will hold up while I am away. I really enjoy DIY projects but my results aren't professional looking by any means. Acrylic is fascinating stuff to work with.