100 Gallon Tank Needs To Be Resealed // Which Silicone Sealant?

Got a wonderful 100 gallon tank from Lars On, and looks like it needs resealing. I've been reading around, and I've been finding that "GE Silicone 1 Sealant for Windows and Doors" has been widely used by many aquarists. Unfortunately, most of the articles I find, are of people fixing up tanks that are less than a 100 gallons. I've read horror stories of people using that same silicone sealant with tanks that are bigger than 100 gallons, and have had their tanks leak or even have the sealant fail on them due to the pressure that the water is giving off...

I've been hearing about the same things for "Aquarium Grade" silicon sealant, but the ones I find are rated for aquariums that are 30 gallons and below.

I can't seem to find a good aquarium sealant for a 100 gallon tank (Glass, btw)... I'm still going with GE Silicone 1, but still very hesitant...

Anyone have any suggestions as to what kind of silicone sealants you've used with tanks that are over 100 gallons? Or tips would be good, I s'pose... maybe I should leave a lot of the sealant on the seams? It doesn't have to look neat, since it'll be covered in gravel/sand, anyway, right?

I'm well aware that I have to remove all the old sealant before I add new sealant, etc etc... I'm just unsure about the quality of the sealant being able to hold a 100 gallon tank together.

We used aquarium grade silicon in college to seal a 150g. it kept that tank sealed up tight for the four years we had it. I went to CWU, and we bought the sealant and the local pet shop, and I can't remember the actual name. I will check with my friend to see if he remembers (but this is a small detail from over 10 years ago) good luck! You nailed it with the removal of ALL old sealant, and then just lay a nice thick bead all the way across. that's what we did.

Thanks lloyd! I tried taking one strip of sealant off, and it was SURPRISINGLY easy, with a razor blade... the youtube videos that I've watched, made it look like it was going to be a real chore.

Either, the old sealant that was on the tank, was so old and brittle that, that's what caused the easiness of it all. I'm really glad I didn't test to see if the tank could hold water before doing anything to it. Hahahaha!!

Since it's a really old tank, it's got a lot of calcium deposits/lime scale/hard water, and what have you... should I clean up the tank first, with a vinegar wash, before I proceed to reseal the tank?

I'd definitely love to know what kind of silicon sealant it was you guys used!

Dow Corning sells a black sealant for aquariums that IMO is the best at resealing old glass tanks. Problem is you have to literaly take apart your tank to get all the old sealant out and the tank has to be perfectly clean before you apply this stuff. Then it takes 7 to 14 days to cure before you can add water. Once done properly that tank won't leak a drop.

Salzabar, yikes. Sounds like a little too much work for me to do alone. Does that also mean that I'd have to take off the panels completely, as in... completely disassemble the tank?

Because I noticed that when I took off one of the sealant strips, the glass panels didn't fall apart. lol!

At least remove all silicone and clean it all up before resealing. When I had to reseal I was working with a 55 gallon so taking it apart was no big deal for me but 100 gallon? I would ask for help.

Slazabar, when you mean remove all silicone, are you talking about, to the point where the glass panels can come off?

Yuppers. All of it or you run the risk of another leak. Laws of physics and a bad silicone job don't mix.

Oh man... I don't know how I'm going to get this done now.

Clean where the old sealant was with isopropyl alcohol to help the new silicone adhere better.

Gryphon: Gotcha on that. Thankfully, all the youtube videos I've seen, have mentioned about using isopropyl alcohol to clean up and residual silicone that the razors can't get.

Thanks for backing that up though!

I have done it twice now and it is really simple. Just follow thie steps in this link.

[You must be registered and logged in to see this link.]

Seems there are 2 steps to sealing a tank. The sealant between the panels and the bead outside the panels. The reading I've been doing on the subject requires a full panel removal. I too have been enquiring about the life of aquarium sealants. My 140 g is pretty old , I often wonder the life expectancy of silicone and glass tanks...

[You must be registered and logged in to see this link.]

Madness, I've read that site during my researching phase, and I don't recall it saying what kind of sealant he uses... upon further observation, it looks like an older version of GE Silicone 1.

But the article, he repairs a 25 gallon tank, which I wouldn't be worried about, if my tank wasn't a 100 gallon tank. hehehe...

theChad, I have not seen this article before. Gonna give it a good read, but as you mentioned, if it comes to taking off a whole panel, that might not work well for me, since I have no help. Maybe I should just get it professionally done? Wonder how much that'll cost.

Yes use silicone 1, NOT 2. My tanks were both 135 gallon. Still very easy.

Get some quotes and share them with us. I'm curious if 1) YOU CAN FIND SOMEONE TO DO IT and 2) HOW MUCH. Since the tank was free...right? Then I would try it myself. If you mess up then you're out the cost of the silicone and your time. The experience points you get from doing this project yourself will greatly improve what you can do in the future when it comes to tank restorations. Google search Dow Corning aquarium sealants or use that GE 1 stuff . Strip out the old sealant and lay out the glass panals on soft material (old carpet, towels, sheets, etc...) clean, clean clean all edges and corners of the panels...did I mention clean? Start with the bottom panel and silicone into the bottom trim ring using a spacer in place of the side glass panals. This way you have room to slot the side panels when you are ready to install them. I used tile spacers measured out the thickness of the side panels. Once the bottom panel is siliconed in firmly then go around with each side panel and silicone them in one at a time using a heavy tape to keep them joined at the corners and a square to make sure you have the 90 degree angles you need to make the box. I used a preform made out of 2x4's that I made prior to performing my tank reseal. Use what you want but just be mindful the silicone sets after a few minutes. Once the sides are up and SQUARE all you have to do is silicone the top ring and then wait at least 7 days before water testing. I would wait the full 14 days in a well ventilated area just to be sure its cured and ready for aquatic life.

Thanks for the tips Salzabar

I'm very hesitant with taking the panels out myself, simply because it'd be my first time to do this, I'm sure I'm capable, just not confident. Hahaha!!

Madness, that brings more reassurance for me

I actually just did this on my 125 tall. It is 4'6" long, 30"h and 18" deep. The top had a frame but the bottom didnt. The first fill was a disaster as the back panel slid off the bottom panel due to the pressure. When this happened the pressure pushed sand along with the water out of the back seal between the two panels so now there is sand in between the two panels for about a 10" section, sketchy at best! Not wanting to remove panels and do it ALL over I went back to the drawing board and fabricated an angle iron frame that fit very snug. I then cut the old silicone out of the tank side and re-sealed it using a .5" radius gauge to get a nice transition between panels, the perks of being a machinist! I then put two massive beads of silicone along the two parts of the angle iron, creating a buffer that has a little bit of give when the glass pushes out, and slid it over the bottom of the tank. Just emptied it last night after a two week test and it is sealed up tight. There is no need to mess with the silicone in between the panels, unless of course it is completely degraded which is unlikely. Oh, and I used GE Silicone I, not II as it has a mold/mildew inhibitor that your fish won't like! Go to walmart, I believe I paid $4.30ish there for a 9.8oz tube as in the pic. At home depot they go for $6 something a tube.

I hope this all makes sense!

Heres the tank:
[You must be registered and logged in to see this link.]

Angle Iron trim with silicone wedge in there:
[You must be registered and logged in to see this link.]

And the silicone:
[You must be registered and logged in to see this link.]

Addicted2CAs, Oh WOW!! Thank you so much for that thorough explanation! That's more reassurance for me . . . one thing I noticed, is that my 100 Gallon tank doesn't have a brace in the middle of the top and bottom portions of the tank. I wonder if it would be more beneficial to add a brace, or I must just be thinking way too much about it, and just tackle the silicone resealing portion first? Hahaha... I get SO paranoid, after hearing/reading all the horror stories that some aquarists have gone through. Woo!!

There's definitely NO rush for me to use the tank, so allowing the silicone to cure is going to be an easy wait for me. I don't see myself using the tank for several months, because I also have to find out if the flooring of my house will support all that weight, once the 100g tank replaces the 55g. We're most likely going to find a way to reinforce the floor through the crawl space. It's a pretty old house (built in 1952) . . . so I'm not confident that houses built back then are sturdy enough to support the total weight of the 100g. . . . assuming that it will weight more than 1300lbs with everything in it.

So yeah, definitely need to check the flooring before anything else. Just figured that I'd worry more about the tank first than the flooring, since my partner knows more about that, than I do...so I'm leaving that portion of the challenge to him. LOL

Oh, also... how I WISH I had a friend who was a machinist. LOL... that frame you made sounds really nice!

No problem. Like you I was a bit skeptical messing with the sealant aswell! I primarily went off that link Madness posted, that seemed to be the most thorough I had found. The tape is also a great idea but I skipped that part because it isnt a show tank to begin with so being super clean wasnt an issue. That brace you see in the first pic is more for reassurance than anything as the tank is only 4 foot. My 160 which is the same dimensions just two feet longer is 5/8" class and didnt come with a support. I made both of those out of quarter in strap steel, doubled up on that top part and welded tabs on to hold it over the sides. They both work like a charm and are much more than I need strength wise! How thick is you glass? I'm assuming its a 4foot tank?

At 100gals I wouldn't worry too much. I believe sagging over time would be more of an issue than something suddenly letting loose. I am more than willing to help people on here that need any type of metal work done such as the brace and frame for minimal charge. People on here take care of me and I would love to return the kind gestures!!

Addicted, It's a 5 footer. The Dimensions of the tank are:
60" Length x 21" in Height x 18" Depth

The glass is 1/2" thick (I'm not sure if this means that it's an old tank... I vaguely remember reading something about how older tanks were made with thicker glass, or something like that... I'm just assuming that it's thick because it's a bigger tank, but since you mentioned that yours is 5/8" thick, I could be wrong. LOL)

the tank is far from being complete, and even if I did have it all finished, I still have to worry about the floor in our house, being able to support all the weight. Hehehe!! Thank you so much for lending out a helping hand! I'd do the same for our community if the chance arises!

Here are some pictures:
[You must be registered and logged in to see this link.]

Yep that is a stout older tank. I found a blurb once that these older thick tanks with no center brace (because of the thick glass) were made by Oceanic which is no longer in business. Not sure if thats correct but sounds familiar!

Anyhow, those seals look just like the ones in my 160 which will be getting emptied here in a few days to reseal. Interesting how the silicone turns colors and shrivels inwards toward the seam slowly removing the seal. Mine is old enough that it is a deep teal!

Good luck and let me know if you would like help. I usually go up past bremerton on saturdays on the way to my folks in sequim.

Addicted: Well shucks, you're a life saver! Hahaha When I tried taking off one portion of the silicon sealant, it really wasn't as hard as I had though. Possibly because the sealant was pretty much flaking off. I'm sure once I start working on the bottom panel of glass, where the sealant is laid on pretty thick, is where most of my blood and sweat will go to. Heh.

As for any help, that would be great! I will not start working on the tank until the warmer months come rolling in, so there's definitely no rush. Perhaps once Spring time starts to warm up, I'll send you a PM if I do need some assistance on the tank. I really appreciate all your help, Addicted!

Do you visit your parents weekly, or monthly?

The problem I ran into was trying to get a sharp razor flush against the glass while still being able to hold it. I ended up using a bunch of electrical tape wrapped around the top of the blade so I could hold it as flush as possible and still be able to push hard. The only other thing to watch for is that you don't push the blade too far in between the two pieces of glass. I pushed the blade in until I could see the tip was about to pass between the two panels and made a sharpie mark for depth.

I usually head up there 2-3times a month.

I've got a raze blade scraper that holds the razor blades in place and allows me get a good grip on the blade w/o worrying about bloody fingers HEHE... Looks something like this:

[You must be registered and logged in to see this link.]

Well be careful with using the GE Silicone 1. Make sure you use a pretty thick beading of silicone. I, too, reseated an old 100 gallon tank about 5 months ago using the GE Silicone 1. Everything was going great until this past Sunday when I woke up to a dripping tank and a newly remodeled room full of water in the carpet. Does anyone have another suggestion on another silicone that may hold up better than the GE Silicone 1? Thanks in advance.

 - Oh, that's stinky. I haven't heard any negative reviews about the sealant itself. But have heard many stories about ppl not getting the tank to seal using the sealant. It's gotten to the point where I wonder about the appliers technic. If there was product out there I knew was better than GE Silicone 1 believe you me I would be using it!! 


Sorry...

Some pet stores will carry a silicone you can use. All articles or videos I've watched, they all used the GE 1. I used it on my 90g, so far, it's good. It is my first tank resealing so hopefully, it stays that way.

Ge Silicon 1 works the best. I reseale my old 185 bowfront and if anything is going to leak it was that monster. I always fill the tank first and look for leaks. If there is none than you are ussally good with just removing the old silicone from the inside of the tank and not dissasimbling the tank. Clean the old silicon from inside the tank carefully and dont jam you blade in between the paines of glass and disturb the silicone there. Clean the glass with a non solovent cleaner, isopropyl alcohol works very well. Once clean use painters tape to layout your seams. Shoot for a 1/4 inch per side. Lay down a nice healthy bead (Bottom/Front/Back). Than wet you finger in COLD water and with medium pressure smooth the silicone into the corners. Let the tank cure overnight and then use a NEW sharp razor run it along the edge of the tape cutting a nice perfect line in the silicone. Remove the tape and leak test the tank again.

Hope this helps Zach

Um.. Guys this topic is old lol. My tank has been resealed for a while now. Go check out the "taming the beast" topic for further updates on this tank. Lol.

Thanks for the extra info though, everyone !

PokeSephiroth wrote:Um.. Guys this topic is old lol. My tank has been resealed for a while now. Go check out the "taming the beast"  topic for further updates on this tank. Lol.

Thanks for the extra info though, everyone !

  - TeriB reopened the thread. Looks like they may have had resealing problems. 

Oh Whoops! I didn't notice terib 's post! Doh. Sorry about that! Carry on... Carry on. Lol!

I too, used GE1 for the 100gallon, and I haven't had any issues so far. *knock on wood* but in case it does decide to flood on me, I have it "conveniently" placed in the garage, so there wouldn't be much of an issue, if the garage were to flood Hahaha!