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If you keep tanks for any
period of time, at some point you will need to re-seal a tank or two. There is
something
in the blood of a
fishkeeper that prevents them from being able to part with an aquarium where the
glass is intact,
but it just leaks. The
problem is that many of us then end up with tanks that leak, or that can only
be filled to a
certain point, etc.
Re-sealing a tank is not difficult, anyone can do it, and as a result of your
effort that tank will last
for many more
years. I have some Plexiglas tanks here that have been resealed 2 and 3 times
over 20-30 years!
When a tank begins to
leak, or worse, opens up along a seam, a repair can be done. A cracked side can
also be fixed,
and I will get to that
later in this essay. Because a mistake can result in, at best, a tank that still
leaks, or, at
worst, a broken pane,
please read through the article before attempting to do any of this!
_________________________________________________________________________________
You will need-
- A package of one sided
razor blades
- Some paper towels that
can be thrown away to wipe silicone on.
- A pair of needlenose
pliars to pull pieces of silicone from the seams and corners
- Possibly duct tape
(depending on type of tanks you are doing) to hold sides together once sealant
is removed.
- Aquarium safe silicone.
I buy the best I can find, and there are a number of truly quality silicones out
there,
made specifically for
aquarium use. The silicone listed as “Aquarium Safe” in home improvement stores
is great
for tanks up to 30
gallons, but over that size it doesn’t work as well and leaks may happen. DO NOT use
a
multipurpose household
silicone. Though some may disagree, I have learned that silicone does vary by
quality,
widely, between
manufacturers. Sealants made specifically for aquarium use are made with a
texture that when
handled correctly does
not easily allow air bubbles to develop, nor does it develop channels or crack
as it
dries (many silicones
do). With a 5 or 10 gallon aquarium, where the water pressure is mild, using
cheaper
silicones can work. With
bigger tanks you are seeking out problems by skimping on the quality of the
silicone.
Also- and this is
important- the process of removing the silicone is time consuming and can be
tiring. If a job
is completed, and the
tank ends up still leaking, it all must be redone from scratch- scraping out and
throwing
away all of the silicone
you just put in, so you want to do it correctly, thoroughly, the first time.
- Dustpan and dry
washcloth. You will need to remove all of the silicone pieces as they clutter
the bottom of the
aquarium. For a good
eventual seal, the entire work area must stay dry. I have found that a dry
terrycloth type
washcloth sweeps up the
sticky silicone most effectively.
- A well ventilated area
to do the work. The silicone can be quite strong smelling giving off all
those
vapors
we are all supposed to
avoid. The tank will also need to stay in the well ventilated area to dry for up
to
48 hours.
- Lastly, a place to test
the tank once it is ready. If the tank is within a close fitting rack or stand,
you
may want a work area
where the tank can be filled to test that it is properly waterproof before
putting it into
use, where all sides can
be observed and watched closely.
Part 1:
- The first thing you
need to do is totally empty the tank, and totally dry it out. Remove every last
bit of
gravel, dirt, etc. The
specifics of problems with larger tanks (50 gallons and over) will be discussed
later.
At this point the same
procedures apply.
- With a one sided razor
blade, remove all of the previous silicone. This is actually easier than it
sounds,
and the more you do it,
the easier it gets. The trick is to easily slide the blade under the previous
bead
of sealant along the
seam, doing one seam at a time. Go back often and do the same along the
adjoining wall
so that you can remove
the old silicone in a long, triangular strip, and do that with each of the 8
seams of
the tank. With corners I
will cut under the sealant from every angle, then pull out the plug of sealant
from
the corner with a pair of
needlenose pliars. Get all of the sealant out of the tank. A cloudy film
on the glass anywhere
in the tank where
silicone will be placed must be totally cleaned- any film of the old
silicone on the glass will need to
be entirely scraped out!
- Plexiglas Tanks- I
treat my Plexiglas the same way as I do my glass tanks with respect to sealing.
However,
a correctly sealed
Plexiglas tank does not show the bead that is routinely seen in a glass tank. To
separate
a Plexiglas tank and
reseal using Plexiglas specific sealant is not what I will discuss here. Because
Plexiglas
tanks generally are not
made as glass tanks are, with a silicone bead along the seams, the first time a
Plexiglas tank is
resealed, I will simply apply the sealant over the previous seams, sealing it
the same way as
I would a glass tank.. I
have sealed up to 20 gallon size Plexiglas tanks this way with success.
• Now BE CAREFUL- once
the sealant is removed from within the tank the razor blade should be able to
slide between
the meeting edges of the
glass, and the glass panes will free up such that with less than gentle handling
the
pane could be removed. On
tanks without an outer frame holding the panes in place, use duct tape around
each
outside corner to hold
the tank together. When leaving for any period of time on a tank of up to 50
gallons,
after the sealant has
been removed, leave the tank sitting in its normal, upright position. I will
usually
turn the tank on its
side, and remove the sealant sitting down in front of it where I can reach into
the tank
easily, so I must always
carefully turn the tank upright after finishing the work before doing
teh resealing.
With 50 gallon+ tanks,
trying to move them unsealed could be dangerous. A pane may become
dislodged and fall
in, or the panes may
become misaligned if allowed it to sit, unsealed, on any side other than
the bottom.
• The panes are generally
not “finished”- the edges are not usually rounded or polished, so contact with
the
edge of a pane must be
done carefully so as not to be cut. If done right, however, you should never
come in
contact with the edge of
any pane of glass.
Part 2-
Silicone does not stick
to itself- putting new silicone on a layer of dried, already cured silicone will
lead to
a separation that will
leak over time. So Step 2 is simply removing all of the silicone that still
exists, but that you
thought you’d removed.
With the one sided razorblade, scrape and polish the glass where the old sealant
had sat, shaving
off any residue that may
be left, cleaning down into each corner. It will come out easily enough- but it
has to be removed.
If the glass below where
the old sealant was is opaque and not clear, a layer of silicone is still there.
I mention this
as a separate step
because the entire job comes down to whether the tank leaks or not when this is
done. When there are
leaks, not having done
this step effectively enough is often the reason why. Some people will use
acetone and rub out
the old silicone that
way. I prefer scraping with the razor blade, changing the blade often, changing
the directions of
the strokes.
After that is done,
totally wipe out the tank. I will sometimes use a hand vacuum to remove every
last bit of silicone
dust from the work done.
Provided the tank is also fully dry, it is time to apply the silicone.
Applying the
Silicone-
Cut the nozzle on the
silicone tube to allow for a healthy bead of silicone. I will use the second
largest gradation
from the base of the
nozzle. Have the number of tubes you will need ready to go. The silicone all
needs to apply in
one shot so that all of
the silicone is connected in a uniformly wet state. Start at one corner with the
nozzle close
to the seam. Gently but
firmly apply the silicone so that it goes out in a thick bead, evenly, firmly
and effectively
filling the seam. Keep
the nozzle close to the inside of the seam so that air does not get between the
silicone bead as
it leaves the nozzle and
rests in the crook of the seam. Do not worry about occasional missteps- it can
be cleaned up
easily later- keep
focused on a continuous thick bead resting in every seam without any bubbling or
air beneath it.
Then, in stages- I will
generally do the bottom first and then the sides, use a finger to smooth out the
silicone into
each seam. Only shape the
silicone to a nice, thick wedge that fills each seam, do not push more deeply
than it takes
to fill the seams and
leave the familiar triangle of silicone around its inner edges. If too much
silicone was initially
applied and substantial
ridges are apparent around your finger, they can be removed and smoothed back at
this time.
They can be difficult to
remove if allowed to cure. Continue around the tank until all seams are done.
Try to complete
within 10-15 minutes.
Ensure that corners are filled fully without any air pockets that might cause
trouble after it is
filled. Then let dry for
24-48 hours.
Larger tanks- Some
tanks over 50 gallons are sometimes made so that they cannot be resealed easily,
so the resealing
process can be slightly
more involved. Essentially, the bottom plate seams often need to be reinforced,
to seal with
the aftermarket sealant.
I realized this may seem counterintuitive, but I have done a number of 50
gallon, 100 and 125s
to find that without
reinforcement, they need to be totally redone. I once did a 50 gallon 5 times
before sealing it
successfully through
reinforcement.
Reinforcing Larger
Tanks
Reinforcement means this.
You will need to go to a glass store, and have pieces of ¼” glass cut in 1”
strips, the
length of each bottom
seam, shorted by 1/2” to give yourself some room to work with. You will need 4
pieces the
length of the longer
sides, 4 pieces the shorter sides. You will probably need about twice the
silicone you would use
without the strips. The
larger aquariums are very expensive, and you are totally reconditioning it, so
the expense is
worth it.
You will be laying down
on the bottom plate 2 strips against each side plate of glass to increase the
surface area of
the bond holding the
plates together. The trick is complete the job without an air channel having
formed. Removing the
strips and re-doing the
job is generally not an option.
Lay a thick bead if
silicone down against the bottom seam about to have the 1” strip put in place.
When laying in the
strip, place the far edge
into the seam and lower the edge to the bottom, to not let any air bubbles form.
Pat in evenly.
Lay a thick fresh bead in
the new seam formed, careful to keep the nozzle near the surface being applied,
to prevent any
bubbling. Lay in second
strip on top of the first, also laying in the far edge first and tiltint it down
to form an
airless bond with the
first strip. Then lay a third bead down on that new seam formed, and carefully
run finger along
to spread it out over the
seam as explained above. Repeat for each bottom seam. Then let dry for 48-72
hours before
testing it.
Replacing/ Fixing a broken pane:
When doing a repair, the extent of the damage may be such that the
fix could cost more than the price of a new tank. With a
tank that has a broken
pane, to have a piece of glass cut with the accuracy required so it will
not leak can easily cost more
than the cost of a new
tank- particularly if the tank is of a size less than 40 gallons. But if
yu have a replacement piece,
Here is what you would
do.
Place strips of tape
around the corners of the outside of the tank, in at least 2 places per
corner. Totally strip the old
tank of its silicone. You
will need to do the entire tank as the silicone will not stick to
itself. Any spots where old
silicone would meet new
silicone could be a place where a leak could develop.
After removing the
silicone, gently run the one sided razor blade between the sides of the
broken pane, gently freeing up
the shards. Remove every
bit of the old glass. When totally clean, slide in the new plate of
glass. be sure to put the new
piece in exactly as the
old piece sat, paying attention to whether the plate is sitting on or
next to the pieces areound it.
When the glass is sitting
as it should, put tape on the outside holding the new pane in place.
Then reseal as above.
There is another option, and though it works it can be very unsightly.
When a tank must be replaced as it is not econimical to
repair, I will study the
break to see if it can be patched. An occasional crack can be covered
with siliconed ceramic 6" tiles.
In a similar fashion, I
have seen others who, rather than remove the broken pane, will silicone
in a new pane on top of the old
one. This way there is no
resealing at all of the seams.
Fixing a leak without
tearing the tank down:
I mentioned there was a
right way and a wrong way to seal tanks. This is the wrong way. But if often
works, sometimes
permanently if not for
just awhile, and it is far easier. Sometimes, if a tank has a small leak after
you have just
finished repairing it,
this way can work so that you don’t need to scrape out all of the silicone you
had just put in.
Still tear down the tank
(at least to below where the leak is. If it’s a big leak, or a cracked plate,
this method won’t
work. After the area
where the leak is occurring can be clearly seen- both, if possible, where the
water is going into
the silicone from the
inside and where it is coming out on the outside, thoroughly dry the area around
the leak, and
clean any glass nearby.
What you are going to do is cover the spot where water is getting out with a
spread of silicone
over the spot that leaks,
anchored to the glass on either side of the previous bead. Then, on the outside,
put a thin
bead over the place where
the water is coming out. Let dry for 24-48 hrs., and retest.
Greg Sage
selectaquatics.com
selectaquatics@gmail.com
Copyright 2013
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