Sealing A Tank

[Foooz]

How difficult is it to reseal a tank? Per the seller it has a small leak at the bottom seam.

[Irishman360]

Originally Posted by Foooz

How difficult is it to reseal a tank? Per the seller it has a small leak at the bottom seam.

Pretty simple. Make sure you get a few razor blades to scrape off old glue then re-seal it with reef safe glue. I used a knife when I spread the glue to create a professional seam. YouTube DIY tanks or sumps for tips on how to seal stuff with glue.

[Foooz]

Thanks Irishman. Do I need to clean the adhesive between the panes or just what is visible and accessible? Should I clean the entire seam or just where the leak is coming from knowing that leaks can migrate.

[shifty51008]

If the tank leaks then you will have to tear the tank completly apart, clean off all the old silicone, and put all new silicone in the tank.

New silicone will not bond to old silicone

[billdogg]

What Shifty said. It IS NOT easy. Although "resealing" a tank by putting down a bead on the inside *might* stop a leak short term, the only way to do it properly is to completely disassemble all 5 pieces of glass, clean them of all traces of silicone, and start from scratch using a silicone adhesive.

IMHO, you are better off in the long run buying a new tank unless you got an exceptional deal on a otherwise very expensive tank. Even then, without lots of practice your chances of success are probably about 50/50 if you've never done it before.

[Foooz]

Thanks. It is a 220g that seller is looking for $225, but I believe that to be negotiable. I will probably stay away from without having the right place and tools to repair.

[MrClownReef]

I'd probably buy it for $225!
The glass alone is probably pretty close to that.

Try to do the disassembley and resealing yourself (or find someone on your local RC group) and let it cure for a few days. Then fill it with water for a couple weeks to check for leaks, before putting livestock in!

[billdogg]

for that price, it might be worth the effort. What I would do is practice first on smaller tanks. Petco is having their $1/g sale - buy a couple in the 10 - 20g range, take them apart and put them back together a few times to get an idea of what you are in for before you even attempt something as large as a 220.

[Irishman360]

Tearing apart the Petco tanks are a lot hard than you think. I broke two panes of glass when tearing one down to use for baffles on my sump. Call local glass shops and see if they can disassemble and re-assemble the tank for you.

[MrClownReef]

I agree petco tanks are tough to disassemble without breaking. Mainly because they build them with very narrow gaps and it is very hard to get anything in between said gaps. Calling a local glass shop would be another good idea, however I feel they might charge you a bit for labor.

[MrClownReef]

When I was disassembling one of my many 40 breeders for sump baffles I broke and wasted about 6" or glass...

[ca1ore]

Originally Posted by MrClownReef

I'd probably buy it for $225!
The glass alone is probably pretty close to that.

Try to do the disassembley and resealing yourself (or find someone on your local RC group) and let it cure for a few days. Then fill it with water for a couple weeks to check for leaks, before putting livestock in!

Few weeks ..... Not days!

[MrClownReef]

Most silicone cures within 48 hours. Why wait weeks for the curing? I'd wait weeks to check for any water leaks.

[stingeragent]

I wouldnt do it unless you were already a pro at it. That is a lot of water on the floor if its not right.

[ca1ore]

Originally Posted by MrClownReef

Most silicone cures within 48 hours. Why wait weeks for the curing? I'd wait weeks to check for any water leaks.

All the professional tank builders I know let the structural silicones they use cure for weeks. Not a job for the inexperienced or uninformed IMO.

[toothybugs]

I did some glass drilling with my Dremel over the weekend (holesaw wasn't being my friend) - I laid down a bead of silicone on Friday to act as a water trap around my drill site, and after I was done with everything yesterday, I scraped it up with a single-edge. The bead was maybe 3/8" and the center half was still gooey yesterday afternoon.

Thin films of silicone cure quickly, but the cure mechanism requires that water vapor travel through the cured film to cure the center. The thicker the bead, the exponentially longer it takes to cure fully.

[Breadman03]

Originally Posted by MrClownReef

Most silicone cures within 48 hours. Why wait weeks for the curing? I'd wait weeks to check for any water leaks.

A small, non structural bead of silicone in your bathroom takes 48 hours to cure. The thick beads in a fish tank take longer, especially since the portion holding everything together is sandwiched between two panes of glass and the acetone has to evaporate through already cured silicone. It takes time. Note the curing info for RTV 108, considered one of the best for aquarium use:12-24 hours before the bond is strong enough to handle parts.

Something else to consider is that during reassembly, you only have a couple minutes to put everything together. Do you feel confident that you can lay down silicone, assemble and clamp a tank that large? I might consider it if I owned the tank, but wouldn't buy such a tank to repair.

[Shawn O]

REMOVAL OF SILICONE ADHESIVES
David Erhardt

REMOVAL OF SILICONE ADHESIVES is a problem which conservators are encountering more and more often. Silicones are thermally stable and difficult to dissolve. Mechanical removal is one possibility. For certain substrates, chemical degradation of the silicone can also be considered.

Silicone resins are decomposed by strong acids such as sulfric or concentrated hydrochloric acid. Decomposition can be accelerated by swelling the resin, which can be done with polar organic solvents. Swelling and acid attack can be combined by mixing an alkylbenzenesulfonic acid, which is comparable in strength to sulfuric acid, with non-ionizing polar organic solvents such as dichloromethane, toluene or xylenes. Alkylbenzenesulfonic acid in non-ionizing solvents is rather unreactive to many metals but aluminum, iron, lead, copper and tin are slowly etched, probably due to traces of water which allow the acid to ionize. Stainless steel seems unaffected, as are the glasses and ceramics we have tested. Some glasses or low fired ceramics which contain carbonates may react, although the mixture can be applied to limestone with no visible reaction unless water is added. Plexiglas, Lexan, Mylar and polyethelene show no effects after contact, although one suspects that the solvents could cause effects like delayed crazing. The mixture should not be used on porous, acid sensitive materials like paper or textiles.

Either organic solvents or water can be used to rinse off the degraded silicone. Water works because the alkylbenzenesulfonic ion is a good surfactant which serves to emulsify the mixture. The choice of rinse will depend on the substrate. Water is the best choice on materials like Plexiglas, but solvents should be used on acid-sensitive materials like metal and ceramics.

The following formula has been used in this lab to remove old silicone repairs from glass objects:

* 10 mL dodecylbenzenesulfonic acid, available in kg bottles from: Pfaltz and Bauer375 Fairfield AvenueStamford, CT
* 8 mL dichloromethane (methylene chloride)
* 5 mL toluene
* 18 mL xylenes

The fumes should not be inhaled nor the liquid be allowed to contact skin.
================================================

BY MICHELLE VELDERRAIN, NuSil Technology LLC
The silicones evaluated were a silica-filled adhesive (SFA), alumina-filled TIM, silver-filled die attach (DA), and a resin-filled adhesive (RFA). Material substrates evaluated were copper, aluminum, and epoxy (FR4). Cleaning solutions evaluated were two common solvents and three silicone digesters. The solvents used were isopropylalcohol (IPA) and xylene. Two commercially available silicone digesting solutions were chosen; each designed specifically to remove cured silicone by breaking the siloxane bonds and dissolving back into silicone digesting solution. These are referred to as D1 and D2, where each contains a proprietary active ingredient. D2, recommended for use below 49°C, is not compatible with certain plastics, and may react slightly with aluminum. Both these solutions are not water-soluble, but are compatible with many composites and do not contain halogenated solvents. The final silicone digesting solution, referred to as D3, is a 1% tetra-n-butylammonium fluoride trihydrate (TBAF) in Dowanol propylene glycol methyl ether acetate (PMA) solution.

Conclusion

Solvents were not as efficient as silicone digesters in removing cured silicone. Each silicone digesting solution dissolved the silicone within 24 hours, with the exception of the DA. Commercially available silicone emulsifiers evaluated may not have dissolved the cured silicone as quickly as the 1% TBAF solution, but they demonstrated a reasonable effectiveness in removing various types of silicone and ease-of-use. Using additional methods such as sonication and/or slightly elevated temperatures can help increase the rate of dissolving cured silicone since microelectronic packages are composed of several materials and the silicone may have limited exposed surface area. A general-purpose silicone emulsifier can be used when taking into account the substrate material compatibility and the cleaning solution’s ideal performance conditions. Research is recommended to determine material compatibility, and ensure that elevated temperatures will not degrade temperature-sensitive chemicals in silicone emulsifier solution.

[Foooz]

Always expecting differing opinions whn asking for advice. It is interesting though on this topic to see such a wide variety. Would like to hear who has resealed a tank and their experience. Would ou do I again?

[stingeragent]

I don't think its a matter of other people's experiences that will help you with this type of project. No offense, but its all up to your own skill. Same way with building a stand. There a plenty of easy to follow plans on here, but not everyone is adept at cutting straight pieces of wood, or getting everything to fit together square. By all means, if you think you have the experience to do it, then there's no reason why you shouldn't. If however, you have never resealed a tank before, I personally wouldn't risk it on that size of a tank. That is just me though. I have resealed the interior seams on a 29 gallon tank before (not the seams between the actual glass panes), it was my first time doing it, and it's been up a couple years now with no leaks. However, if I would of had to reseal the actual seams between the glass , there is no way I would of tried it. Can it be done? Absolutely, but you ultimately have to make the call if you have the capability to do it, because irregardless of how many people have resealed a tank on here, unless they actually come over to do it for you, your results will not necessarily be the same.

[blt4ever]

Originally Posted by stingeragent

you ultimately have to make the call if you have the capability to do it, because irregardless of how many people have resealed a tank on here, unless they actually come over to do it for you, your results will not necessarily be the same.

My thoughts exactly. I have dissasembled and resealed a 125 I got for $20. I personally didn't think it was that big of a deal, a good friend of mine found a 180 that was leaking and going off the fact I had recently resealed a tank he tried and ended up breaking the glass. If you are extremely patient and have a good focus on details I say try it. After its apart make sure there is 0 old silicone left, clean it all with acetone and put it back together. I used ge scs1200 on mine and after 4 years its still holding. All comes down to how patient and detail oriented you are imo.

[DrPheel]

Originally Posted by Foooz

Always expecting differing opinions whn asking for advice. It is interesting though on this topic to see such a wide variety. Would like to hear who has resealed a tank and their experience. Would ou do I again?

I also did this on my 70G cube build , I got a used rimless cube that I did the reseal myself for the first time. IMO , buy a old 10G and practice on it. They area a few nice vids on YouTube ( https://www.youtube.com/watch?v=I3nNJ0PRhB0 ) This is the one I followed and the tank has been running since June. My tank did not have a leak tho , so the integrity of the seal between the panels was not compromised. Please pay close attention on how to take silicone out since you can do more damage then good to the tank itself. I would suggest you use a quality silicone like SCS1200 with high tensile strength. I only re-sealed it for aesthetic reasons and peace of mind since the tank was used and rimless. I did have to start all over again since I did not like how the bead of silicone looked on my first try. Once you have pushed in the bead in the crack between the tape lines , take the tape off as quick as possible as it tends to stick and screw up the line.

Just my 2 cents

Happy reefing !