Aquarium Re-sealing


May 20, 2009
Wisconsin U.S.A.
My aquisition consists of a 75 gallon all glass tank and stand.
Total cost including gas to go pick it up $46
$26 for the tank and stand $20 for the gas.

Here it is at the beginning.

Now as with all of my used tanks, I will be resealing it. I am in the process of scraping the old sealer out now.

Just figured I'd show the progression of how I deal with used tanks. Because "used tanks" are by far waaaaay cheaper than new.

In my honest opinion used is the only way to go. Cost wise that is.

First off I take over my kitchen table. (not married so I kin do this heh)

I tip the tank on its side for easier access. (note my little helpers )

The tools I use are nothin more than a straight razor.

Now that we have that covered. I begin scraping the bottom seal. Then the 4 upright corners. Now yer gonna wanna take yer time.

Initially you will get nice long strips of silicone peeled out. Like this...

Now for me thats not good enuff...I go back and get the corners good and clean.

Now I've been asked in the past "Won't the tank fall apart?"

If the top frame and the bottom frame are in tact. I have never had a tank fall apart yet.

You need to remove all the silicone from the glass surfaces. Silicone will not bond to silicone.

Here is a pic of a corner, after the initial scrape. When you get the big strips.

There is still a bunch of leftover silicone that needs to be removed.

Here is a pic of the same corner after final scraping.

Note that the silicone "between" the two panes of glass is still there. (Also why it will not fall apart)

Now from past experience, I have learned that when you think you have it cleaned enuff. You dont!! Grab a "NEW" straight razor and try again. I am certain that you will get a little more silicone off yet.

After final scraping with the razors. You will need to clean up all of the corners/seams, where the new silicone will be applied.
Acetone works great, so that's what I use.

Next you will need silicone. Now there is "Aquarium Silicone", but I dont like the expense. So I use just plain old 100% Silicone. You just wanna make sure that there is no additives...i.e. mildew/mold preventers.

"100% Silicone"

Now cut the tip off at an angle. Then proceed to seal your joints. The most common mistake made when siliconing anything, is to drag the tip rather than push it. Dragging causes air gaps! (which is NOT good)

When siliconing anything ( fishtank, bathtub, windows etc.), PUSH it dont pull it. I tried to get pics of this but they just didnt turn out. (go figure)

It's like this, you have a gun (caulking gun). Place the angled tip into the corner you are going to seal. Start squeezing the handle. Then push the gun the same direction it is pointing. By the time you have gone a few inches you will have the feel for how fast to move, and how fast to squeeze the trigger.

I do the four corners first. I start at what is the top of the tank and work down to the bottom pushing my silicone bead all the way. When I reach the bottom corner, I let the tip rest for a second or two (you'll end up with a glob there) which is good. Pull the tip out to one side. Then move to the top of another of the four corners, repeat till all four corners are done. Now for the bottom seam. I start in the center of one of the longer panes. Starting there lets me build the corner glob as I turn the corner. It is also easier to finish the seal where you started if it's not in one of the corners. Continue squeezing and PUSHING pausing slightly to build the corners as you turn. Until you reach your starting point. When you do slightly pick the tip up to overlap the start of your silicone bead.

That's it!!!! Now some folks like to dress their seams (I dont). You kin "dress" your seam with a plastic spoon (dipped in water). Take the spoon and drag it over your silcone bead keeping enuff force and tilt to spread your bead evenly.

This is a new seal on my 75 Gallon.

In about three days it will be ready for "the water test"
I wait three days just to be sure 24 to 48 hours is the recomendation on the package.

The end results....
After adding water, sand, wood, plants and fish!

Something to truly enjoy in the livingroom.

I just hope this is useful to someone....
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May 4, 2009
Gosford, NSW
good job there! also, if you want the silicon to have straight lines, i mask the area with masking tape, gives nice clean lines - just be sure to remove it while the silicon is still 'wet' lol


Jan 15, 2011
excellent report - explained really clearly. I have never seen just normal silocone used... how did you test it wouldnt harm your fish? Bet you saved a packet! Fantastic deal on the tank and stand aswell...the person you bought it from might aswell of given it away. Respect to you and you new tank. cole


Apr 21, 2009
What is acetone? Where can i get it? Is it harmful to fish?
Acetone is a solvent, similar to paint thinner. Also found in some nail polish remover. In the US you can get it from paint or hardware stores. It is harmful to both fish & humans. For fish, only if you pour it straight into the tank though & even then it must be in a significant quantity. Some medications use acetone as a solvent. For humans, the vapors are highly flammable & noxious. Exposed to enough fumes (like everyday for an extended period) can result in brain & nervous system damage. It evaporates rather quickly though and once evaporated I don' think the reside if too toxic.


Nov 9, 2010
sydney, Australia
So acetone is good to use?

Its just that i resiliconed part of my tank but wasnt 100% happy with it so i stript it again.

Now its left a slippery residue.

So i use acetone to remove it?