FAQs on Glass Aquarium Repair, Chips/Cracks
Related Articles: Aquarium
Repair, Acrylic Aquarium
Aquariums, Marine Tanks, Stands and
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Systems, Designer Marine tanks,
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Related FAQs: Chips/Cracks 1, Chips/Cracks 2,
3, Chips/Cracks 4,
Chips/Cracks 5, Chips/Cracks 7,
Chips/Cracks 9, Chips/Cracks 10,
& Glass Aquarium Repair 1, Glass Aquarium Repair 2, G lass Aquarium
Repair 3, Glass Aquarium Repair 4, Glass Aquarium Repair 5, &
FAQs on Repairing Glass Tank: Scratches/Blemishes, Cross-Braces, Leaks, Whole
Panes, Tools: Cutting Glass,
Silicone, Moulding/Frames; Techniques; Olde Tank (Slate Bottom, Metal Frame,
Pecora...) Repairs, Troubleshooting/Repairs, &
Repair, Used Aquarium
Dear Bob and Crew,
Thanks so much for your very informative website. Your time is very
much appreciated. I write to you today concerning a 70 gallon
aquarium (36 inches long x 18 inches wide x 25 inches tall; 3/8th inch
glass ) that has been constructed with the front and side
panels made of low iron glass. The tank is about three years old and
was made by Oceanic. I recently moved and it appears that in my move I
managed to cause two conchoidal fractures on the lowest part of the
font panel of the tank on the inside, resulting in two "half
moon" flakes, one the size of a nickel, the other the size of a
I am not positive, but I believe these flakes to run all the way to the
edge of the glass, where it meets the silicone of the bottom front of
At some point I must have inadvertently knocked live rock against the
lower front panel. I have read the WWM FAQs regarding chips, cracks and
tank repair but it seems that most of the people that have written you
have these cracks on the outside of their tanks. What do you think
about a conchoidal fracture in this location?
<Can be bad>
Is it time for a new tank?
<That or a repair, turning the tank around...>
I am a graduate student and I am on a tight budget. Do you think I
could run internal bracing (a square glass rod) across the front of the
tank and seal it somehow to simply reinforce the tank?
<I do... of course cutting out the present inside Silastic bead in
the corner (NOT that between the glass faces>
Thanks in advance,
<Welcome. Bob Fenner>
Crack in tank
Hi Wet Web Media
I have just got a 70 gallon marine tank that has a crack coming
from where the bulkhead was drilled. It doesn't leak at
all, it's about 6 inches long.
I'm pretty sure if I leave it filled it will just grow and
<Or worse, "spider" out and have the hole panel fail at
Would another panel of glass silicone on the inside
<I'd place outside... overlapping the present crack>
prevent this and ensure this tank will not crack and leak.
Being the back panel that will be painted blue, it doesn't have to
look that neat.
<Have you read on WWM re this sort of repair? Not hard to do, nor
uncommon. Bob Fenner>
500 Gallon Glass Repair or Total Loss?
You guys have been amazing help in the past and I wanted to run
these complicated issues by you. My aquarium is 500 gallons made
of 3/4" glass.
It is beyond heavy. I have the following issues and will attach
photos as well:
1). Is the cross support ok?
<Mmm, likely so... though I would have had the piece of glass
here extend all the way to the front pane... i.e., not had the
1/4" gap filled w/ Silicone, but the two pieces of butted
glass with only a bit between>
2). Is the fracture repairable.
<Mmm, also likely. I would Silicone (tilt the tank on its
side, apply weights (books) over the piece Siliconed onto the
existing pane, over the fracture... an added pane of at least six
inches overlap left right and up, and flush all the way to the
1). Take a look at the first 2 pictures and the notes I added to
The tank was built by Lee-Mar.
<I know these folks well. They make good tanks>
However this cross support does not look like the rest of the
I think the previous owner may have rigged this cross support up.
Despite the fact that there is a 1/4" gap between the cross
support and the inside edge of the front and back panes of glass,
it looks like there is enough silicone and glass sandwiched
together support the weight of a continent or two...lol. Does the
cross support look sturdy to you?
<Again, I wish there was almost no gap here. IF you have
occasion to cut this away, get a closer fitting piece>
2)....the more worrisome issue. This fracture is my fault. The
forks on the material lift I used to move the tank rubbed against
the bottom of the front pane of glass causing a 1.5 inch clam
shell fracture. The fracture does not appear above the bottom
pane or into the water line. It extends from to bottom of the
tank to no higher than the thickness (3/4") of the bottom
pane. This makes me think that the integrity of the glass is not
compromised to the extent that the tank could burst.
<Hard to say... one does NOT want any line fractures in this
However it did slightly break the main silicone seal between the
panes of glass. I water tested the tank and it was ok until I got
about 300 - 350 gallons in it.
The pressure of the water caused a slight drip. Surprisingly it
did not leak out of the front of the tank at the bottom where you
can see the opening in the glass.
<Not surprising actually... the water will exit from wherever
This opening was finely crushed/powdered glass shards that I had
removed. The leak was actually coming from the bottom of the
glass between the front pane and the bottom pane. However the
bottom pane of glass is not damaged so the leak must be coming
through the silicone.
<Yes, around a seam>
The fracture must have broken the silicone seal here just a
little. Replacing the front panel is cost prohibitive and the
glass would be over 400 pounds making it an impossible job to do
in my garage. I would have to take it to a shop hundreds of miles
away. This means I can never reseal the silicone *between* the
glass. However I can reseal the silicone run along the inside
corners of the bottom and sides of the tank.
<And the outside with the added pane>
Would this create a permanent enough seal?
I was also considering laying a small square piece of glass on
the bottom piece of glass and siliconing it to the front inside
pane just above the fracture.
<A useful approach as well... making the front the back of
This means I would have the new silicone seal and glass sealed to
the front panel maybe strengthening this area a little and
sealing it off better. I was then going to pump silicone
or epoxy (do you know of a good brand or will silicone
<Just Aquarium Silastic/Silicone>
into the open fracture just above the bottom plastic piece as
seen in the photo.
<See above... with a pane over all this work, extending a good
half foot plus left, right and above>
This opening is very small, maybe a millimeter tall and half an
inch wide and obviously not deep into the glass. There is no
leaking here but I want to reinforce this area. What are your
thoughts? Repairable without replacing the glass?
<I do hope so>
I want to set the tank up in my house but if there is any doubt
that this fix wont work forever then I will keep the tank in my
garage where it will do less damage should it leak.
<... OR kill or injure someone should it rupture>
I also read that to remove the current silicone run along the
inside edges of the tank I should use a solvent. If this is
correct. what kind?
<... Sharp single edged razor blades and likely
If I apply too much solvent, could it leak between the panes and
deteriorate the silicone between the glass?
<Apply it/this organic solvent with clean paper towels, only
slightly dampened, only to the areas where the old Silicone has
been cut away. You do NOT want it to pool>
If so should I just stick with a razor blade and no solvent?
Thanks for your assistance with this. The damage to my tank makes
me nauseous and I pray I can fix it.
<Worth trying. Do take your time here. Bob
Re: 500 Gallon Glass Repair or Total Loss?
Thank you for the fast response.
So it sounds to me like there is no guarantee this will be a
permanent fix but it "should" work in theory.
<This fix is permanent. It will work or no>
I have attached another image for clarification. The image is a
cross section of the tank. The blue areas being the front,
bottom, and back of the tank.
The red pane on the inside of the tank was what I was thinking to
do. If I understood your response correctly, you are saying to
add the outer (red) piece of glass and have that extend 6 inches
up, left, and right?
If so, how thick would you suggest these extra panes to be?
<Best 1/2". BobF>