Re-Sealing an Aquarium

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JasonR created the topic: Re-Sealing an Aquarium

Re-sealing an Aquarium

Got a leaky aquarium or is the silicone in bad shape? Maybe you found a great deal on a used tank, but you’re not real sure about the integrity of it. Well, you could put your DIY skills to work and re-seal it and breathe many more years of life into the tank for minimal cost.

Re-sealing an aquarium may be an intimidating task, but it shouldn’t be because it is fairly straight forward and simple with a little patience. This step by step guide will address the replacement of the silicone on the inside corners of a glass aquarium.

Before you take this task on you need to know what the problem is with the aquarium and what you are trying to accomplish. If the tank holds water, but the interior silicone is in bad shape replacing it can give you peace of mind. Very minor leaks can also often be fixed using this method. A major leak where there is an obvious serious issue with the bond between the glass panes is a more difficult problem that involves breaking down the entire tank and rebuilding. I won’t get into that here. One thing to keep in mind if considering this is that it is important to replace all of the silicone even if only part of it is bad. If you try a partial replacement often you will encounter problems with where the new silicone meets the old as it does not create a very good bond. People have had success with partial re-seals, but I would rather not take the risk.

Tools & Materials

If you’ve decided to move forward with re-sealing your tank here’s what you’ll need:

Razor Blades

Acetone or Rubbing Alcohol

Paper towels (I use the blue "shop towels" as they are strong and don't shed near as many fibers)

Scrub pad

Vacuum

Silicone (GE Silicone I, Momentive RTV 108, Dow Corning 732)

Caulk Gun

Rubber gloves can be useful

Some sort of caulk smoothing tool or your finger

Masking tape (optional)

Patience!

Stripping & Cleaning the Joints

The most important part of this process is going to be cleaning and prepping the surface. New silicone does not stick to old silicone very well and so it is vitally important to remove all of the old silicone (this part will take the longest). Using a razor blade you are going to work the blade underneath the existing silicone. It is very important that you don’t cut into the silicone sandwiched between the glass panes so you are going to start on the glass pane that butts into the adjacent pane. So once you get through the silicone the blade should run into the adjoining glass and not in between them. You’ll separate the silicone from the glass all the way down the seam then begin working the other side of the seam cutting just deep enough to free the silicone. The silicone should then come out in long strips. Employ this process for all of the joints inside the tank. Once the bulk of the silicone is off then it’s time to get really detailed and scrape off all of the residual silicone. Once you think you have most of it vacuum the tank out. Then clean all the joints with the acetone or rubbing alcohol, scrub pad, and paper towel. This is where you’ll discover silicone that you missed. Repeat this process until you are confident you’ve gotten all of the old silicone off and the glass is completely clean. Do one final cleaning of the joints with alcohol and allow to completely dry (a couple of hours is recommended). From this point on it is important not to touch any of the glass where you’ll be applying the new silicone as oils from your fingers will hinder the adherence of the new silicone.




Taping for Clean Edges

This next step is optional but can be used to get neat lines on your silicone if you’re not confident in your ability to lay a consistent, neat bead of silicone. Basically what you’ll do is lay strips of masking tape down along each joint approximately ¼” - ½” away from the corner depending on how big of a bead you plan on laying down. I recommend wearing rubber gloves while doing this so you don’t mess up your nice clean joints. Clean the joints once again with alcohol and paper towels just to be sure. Refer to the pictures below as an example of what the masking tape should look like. It is important to remove the tape as soon as all of the silicone is in and smoothed out. If the silicone gets tacky before you remove the tape it will make a mess of your beads and if left in then you’ll have tape siliconed to your tank.

Bottom corner tabs:


Fully Taped:



Acceptable Silicone

The type of silicone you use is very important in all this for the safety of your fish and the strength of the bond. There is a lot of debate out there as to which are most effective but I’m just going to give you three options that are widely used among aquarists and are safe for your fish:

GE Silicone I (Window & Door) – Widely available at most hardware and big box stores (probably the most commonly used by aquarists)

Momentive RTV 108 – An industrial grade adhesive silicone that is twice the cost and not readily available in stores (used by professional aquarium builders)

Dow Corning 732 – Another industrial grade adhesive silicone that is twice the cost and not readily available in stores (used by professional aquarium builders)

**It is very important that any silicone you get is 100% silicone and does not contain Bio-Seal or any mold or mildew inhibitors as these will kill your fish. Any silicones that say Kitchen and/or Bath contain mold and mildew inhibitors so do not use these. Look for Window & Door and make sure it does not say Bio-Seal. Read the label thoroughly to insure this is not the case. One thing you will find is that the GE Silicone I does say that it is not for use below the waterline or for aquariums. I assure you they added this warning for liability reasons and that’s it. It used to say safe for aquariums, but due to improper use changed it. It is widely used and safe if allowed to cure properly. If you’re unsure about this get some aquarium silicone from your LFS, but you’ll be paying 2-4x the price for the exact same product with a different packaging.

Sealing

The silicone process is pretty straight forward and easy. Make sure you are outside or in a well-ventilated area such as a garage, as the fumes are very strong. I start by running a continuous bead all around the bottom four horizontal joints slowing at the corners to get a little extra in them. Once this bead is in, grab your tool or use your finger with a rubber glove on and smooth this entire bead out. Now lay down your 4 vertical joint beads starting in the bottom corners and running the beads to the top of the aquarium then smooth all 4 joints out. Immediately after getting all the silicone in and smoothed out you will have to remove the masking tape if you used it. It is important that you remove the tape before the silicone gets tacky or it will make a mess of it.



Water Test

That’s pretty much all there is to it. Now it’s just a waiting game allowing it to cure properly. I highly recommend giving it a full 7 days to cure. You may find that people will say 48 hrs or even 24 hrs, but this is very much bead size and condition based. I find that it’s better to be safe than sorry because if it doesn’t cure properly you’ll spring a leak and be repeating this process all over again. After 7 days you can start your water tests. Begin by filling the tank and watching for any leaks during the process. It’s very helpful to put newspaper below the tank for detecting leaks. I like to fill it half full initially and let it sit for a couple of hours. If you don’t see any leaks then commence to filling it all the way and leave it for a couple of days to monitor for leaks. Obviously it’s going to beneficial to have the tank in a location where leaks won’t destroy anything like outside or in a garage. After a couple of days if there are no leaks drain it and get it all set up for your fish!
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Miss Nicki replied the topic: Re: Re-Sealing an Aquarium

GREAT Job Jason!!!!

Lets see about moving this to helpful articles!
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  • JasonR
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JasonR replied the topic: Re: Re-Sealing an Aquarium

Thanks Nicki! I was re-sealing the 90gal I picked up and thought maybe I should put together something for OFL because I remember how difficult it was to piece together the good information from the web on this for the first tank I re-sealed. Hopefully people can find this useful. I'll probably edit it for the next several days as I think of other info that should be included.

Thanks again! :)
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Miss Nicki replied the topic: Re: Re-Sealing an Aquarium

Let me know when you are done editing...
:)
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spirogyra replied the topic: Re: Re-Sealing an Aquarium

Re-sealing used to be such a pain when they used that black goo back in the 19th century (slight exag) RTV is such a joy and useful for so many other repairs as well.

A few years back I found a roughly 60Gal terrarium near a dumpster behind a strip mall. It had a badly broken side pane (probably once used as a waiting room ornament/lizard habitat)

I took it home and sistered a sheet of lucite plastic over the shattered area with a tube of windshield RTV I found laying in the street one day whilst bicycling to the bank. I RTV'd over all the existing joints after a thorough cleaning, reinforced the outside corners with some left over sheet metal drip edge from a re-roofing project, gluing it also with the free RTV still remaining and built a rather strange looking support system for the top from 3/4" PVC sprinkler system pipe.

I used this as an aquarium for several years with a similarly contrived solar heating system made from a coil of black plastic tube. One year my wife decided that it was an eyesore so I put it outside near the driveway where it once again became broken.....this time from a falling piece of pine tree.

Perhaps it was fate......terrariums less substantial than aquariums...TIM
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benmcfadden replied the topic: Re: Re-Sealing an Aquarium

nice guide dude

Haku, I knew your were good.
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shawn79 replied the topic: Re: Re-Sealing an Aquarium

really good info. think i might have to do mine... :sick:
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Small Fry replied the topic: Re: Re-Sealing an Aquarium

Nice one Jason. I had to re seal my 75g and those are the steps I used. It was a lot easier then one might think, just a wee bit nerve racking when yoiu go to put the water make in for the big test. I would suggest you use a mask when sealing big tanks since you have to kind of stick your head in to chalk the edges and the fumes are brutal. I got dizzy and I thing I took a few years off my life LOL!!!! :sick:
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spirogyra replied the topic: Re: Re-Sealing an Aquarium

Small Fry wrote: and the fumes are brutal.


I'm not sure why, but I rather like the smell of vinegar. Maybe it's because there was a vinegar "factory" near the high school I attended..."AH..the smell of vinegar in the morning.....the smell of VICTORY" FFCOPPOLA paraphrased
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Small Fry replied the topic: Re: Re-Sealing an Aquarium

The vinegar I can handle it is the fumes from the aquarium safe silicone that are brutal :(
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