Cracked sump: Can we fix it?

[cypher1024]

Hey guys,
while cleaning the sump for our new tank, my brother spotted a crack in one corner (of the sump). I think it must've happened while test fitting it in the new stand becuase I know it wasn't there when we bought it or when I was installing the partitions.

I can't find a camera, so here's an illustration of where the crack is located:

It's in the corner of the heater chamber, which I would have thought was one of the strongest points in the sump since there's that baffle only a few inches to the right of it that seals along the bottom of the tank and up both sides. It's a 30 gallon tank (3'x1'x1.5'), and the cracked section is about a 3"x3" (75mmx75mm) square. The glass is 1/4" (6mm).

Now here's the fun part: Can it be fixed, and if so, how?

The only idea we've had so far is to sandwich the cracked section with bigger pieces (say 5"x5") glass. I figure that if installed correctly, even a single piece inside should be able to cope with the water pressure from the heater box (about 6.5 gallons or 25 litres).

Any ideas would really be appreciated.

Cheers,
- Luke

 

[Cashlaw]

Is the crack just on one pane of glass, or does it cross two panes of glass?

I just patched an old 30G that I had managed to crack with a dropped piece of slate. Cracked in about the same place as your pic.

I tried a glass patch first, cut from some scrap glass I had, but it was actually a real pain to get the silicone even across the patch and the original glass without trapping air bubbles. It looked like crap, too, since you could see the silicone through the glass patch.

Took that off, then used a ceramic tile, 4" x 4", placed inside the tank. The tile was easier to patch without bubbles. Maybe because it had small ridges on the siliconed surface . . . filled them with lots of silicone, smoothed that over and put the tile in place, beaded the edges, and it was done.

Seems to be doing fine a couple of days later.

 

[cypher1024]

Thanks Cashlaw.

Yeah, it is just one pane that's cracked (the front pane in that picture). There are a few chips in the bottom of it and it looks like one of them has started the crack. It doesn't extend all the way to the left side of the pane though, so hopefully I can drill it to stop it cracking further.

I'm not too concerned about how it looks when it's done, just that it's watertight and safe. I'll have to see if I've got any ceramic tiles lying around....

 

[hybridtheoryd16]

Since its a sump and looks are not high on the important list.

I would have no problem piling up a few tubes of silicone on the inside of that area. Just make sure everything is really clean before hand and wipe down with some denatured alcohol right before the application of silicone. And pile the silicone up in the corner. Once you do that let it dry for about a week or so because of the large depth of sealant.

If you needed the added security you could laminate another peice of 1/8-1/4" glass on the outside a few inches bigger than the cracked corner square. With silicone and some weight to squeeze out any air traped between.

i have done something very simular to this on the back corner of a 75g tank. Where all three panes (bottom,front,side) had there corner cracked and missing. You could stick a pencil thru the hole it left. And it is still holding after 3 years.

 

[cypher1024]

Awesome. It's reassuring to hear that this sort of thing has been successfully done more than once. For a while I was worried that I was going to have to tear the sump apart and get the sides cut down and then reassemble it all.

 

[cypher1024]

I finally borrowed (stole) my brother's camera so I could get a shot of the patched up sump. It's not pretty, but it's behind a door so it can't be seen. The main thing is that it holds water (which it's been doing for about a week now).

Thanks for your help guys!

 

[Cashlaw]

Cool!!!