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FAQs on Glass Aquarium Repair, Silicone/Silastic... Aquarium- Use 100% (Aquarium Use) ONLY,  7

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Related FAQs: Silicone/Sealant/Sealing 1, Silicone/Sealant 2, Silicone/Sealant 3, Silicone/Sealant 4, Silicone/Sealant 5, Silicone/Sealant 6, Silicone/Sealant 8, Silicone/Sealant 9, & Glass Aquarium Repair 1, Glass Aquarium Repair 2, Glass Aquarium Repair 3, Glass Aquarium Repair 4, Glass Aquarium Repair 5, & FAQs on Repairing Glass Tank: Scratches/Blemishes, Cross-Braces, Leaks, Chips/Cracks, Whole Panes, Tools: Cutting Glass, Moulding/Frames; Techniques; Olde Tank (Slate Bottom, Metal Frame, Pecora...) Repairs, Troubleshooting/Repairs, & Acrylic Aquarium Repair, Used Aquarium Gear,


20 Gallon with Lots of Air Bubbles in the Seal    10/4/16
I recently had to move my fish from a 20 gallon MarineLand with a defective seam (caught it proactively, thanks to the WetWebMedia FAQ!), and purchased a 20 gallon Aqueon and promptly moved everything into it on 9/25/2016.
All in all, it was a successful move, but last Thursday, I glimpsed at the back of the tank and noticed what could be another seam problem!
<Oh, no!>
I contacted MarineLand and they with hesitation refunded my tank (purchased in 2014),
<That's very generous of them. I would think that 2 years would be past the warranty date...>
and am now wondering if I should contact Aqueon about my seal. I really don't want to come home to a puddle of water, but I also don't want to needlessly keep returning tanks for silicone issues and moving everything from one tank to another. It's a lot of work, but certainly better than a blow out.
<I know how you feel. It's a pain, but it's for the good of your home>
I took a few photos. Please note, this is on a portion of the aquarium that is facing the wall, so it's very difficult to get a good straight shot of the seams. The first two pictures are from 9/29, the second two are from 10/3. For some reason, the irregularity in the seam is more pronounced on the 9/29 photos. I had cycled the tank in between the two pictures.
<Looks like it is just some air bubbles. Some of my seams have the same problem>
Is issue in the seal between the glass something to worry about? I'll gladly take more pictures if necessary.
Tom in Portland
<Tom, I think at this point it is up to you. With these aquariums being on the cheap(er) side, you can't expect them to be perfectly made without any problems at all. If you want to go to the trouble and you're worried about a leak, by all means, replace the tank. I personally would not replace it, as it doesn't seem (no pun intended) like it will be a problem, and because it is a smaller tanks. If it were a larger tank, even like a 55 gallon or higher of course, I would definitely look into it. That's the best advice I can give to you. I am not sure how Aqueon would handle this sort of claim, but if you are seriously worried about an issue, contact them. Good luck with the tank and the seam issue. Cheers, Gabe in Ohio:)>
<<Well-stated Gabe. BobF>>


Re: 20 Gallon with Lots of Air Bubbles in the Seal      10/5/16
Thanks for your prompt reply, I appreciate the input.
<My pleasure. Any time, my friend.>
I was leaning on not worrying about it, but wanted to double check before I put it at the back of my mind.
<I don't blame you. I would've done the same as far as investigating goes.>
While I certainly was not looking forward to anything like a leak, my main concern was a major blowout. Not sure if that would even be likely in an aquarium this small even if the seams were defective?!? Do you know?
<Considering the size of the tank, I wouldn't worry about it. Don't overthink it, Tom. You'll find that you're too stressed to do anything else.>
As far as the old Marineland goes, they were indeed very generous in their refund. I had purchased one of their BioWheel kits with an LED light hood, heater and filter, and they are refunding the whole package due to the seam issues (Giving me the opportunity to upgrade my lighting system!). I'm not even sure how big of a problem it could've been, but opted to inquire with them, and their responsive was nothing short of impressive. I'm so happy with their sense of accountability, I would've purchased another Marineland, but it appears none of the stores in Portland carry Marineland tanks, with the exception of the combo kit and some tanks that are 55 gallons and up, hence the Aqueon.
<I understand>
Anyways, thanks once again for your response and keep up the good work!
<Tom, good luck with the tank. I hope everything goes well in the future with the tank. Let us know if you have any other questions! Cheers, Gabe>

Tank seam concern      9/16/16
Hello and the usual thanks for all you've been doing for the hobby over the years!
I bought a used tank recently, and though I inspected it as best as I could in a dim garage, I have a concern about one of the seams now that it's home and partially filled. I've been Googling for over an hour trying to see if anyone has even seen something like this before, and I'm not finding something similar. I'm attaching a picture.
The tank is a 57gal rimless, and there is what can only be described as a "scratch" beneath a strange air bubble near the top of the front left seam. I have the tank ~75% filled and the water level stops just below where the scratch ends. I know the top part of the seam isn't nearly as stressed by water pressure as at/near the bottom of the tank.
I've monitored it and in 24hrs, it hasn't grown. I'm debating whether I need to cut my losses to be 100% sure I don't flood my apartment sometime in the future if the seam should fail. I'm also not sure how a seam could end up like this--it almost is like the seam is splitting in two vertically, but I'm trying to wrap my brain around what could possibly have
happened to make a cured bead of silicone achieve that feat. Before I concede failure at scoring an incredible tank and blowing it during my inspection, I figured I'd ask the experts at WWM if you've ever seen this happen to a seam before and if you think the tank is in need of being scrapped as-is for safety/integrity concerns.
Thanks much!
Joe Schneider
<Well; this vacuolation is a concern, but I'd use this tank... will not likely fail for many years.
Bob Fenner>

Tilted up for pic

ADA tank seams     5/24/16
Dear WWM crew,
I just bought a new ADA fish tank 90cm x 45cm x 45cm a month ago.
This week I started to notice something about the seams, especially around the corners of the tank, that I am not sure how to explain. Due to light reflections, some areas of the seam does not look as nice as others, and some parts of the seam appear dirty. They appear a lot worse in the pictures attached than to the eye.
I am very worried about these "defective" parts of the seams and the safety of the fish tank. Can you pls take a look at the pictures and let me know.
I sort of expected ADA tanks to be more perfect looking, but it is mainly the safety I am concerned about.
<Mmm; well; though there are some apparent less than perfect sealant areas, this tank is fine; not likely to fail>
Hope to hear from you soon.
Best regards,
<And you, Bob Fenner>

Re: ADA tank seams     5/25/16
That's good to hear, thanks Bob!
<Welcome Kar. B>

In quest of greater knowledge of silicon seams      2/1/16
Hello WWM Crew,
<Hey Eddie>
Thank you so very much for all that you do in your service to aquarists everywhere. I have what may seem like a fairly ridiculous request today, but I’m going ahead with it nonetheless. I have attached two photos (I tried to keep them to just a few hundred KB’s as requested.
There used to be instructions on WWM about how to resize photos, but I couldn’t find them. I ended up cropping them which reduced them from over a MB to what they currently are). These are of a old 10 gallon aquarium.
<Glad this is a small tank>
I’m not exactly sure how old. It was given to me six years ago, and was several years old at the time. It has been in use most of this time, in my daughters’ room. Her last fish, after a long and happy life, died, so we decided to move the tank and set it up in the dining room with a few freshwater fish for the family to enjoy. As I was cleaning it, I noticed some air bubbles/pockets in two of the seams that concerned me. The first picture (0691) is of the left front seam, where the bubbles seem the worst. The bubbles run a couple of inches down. They disappear when the tank is emptied below them, and reappear when it is filled.
<Yes; air embedded here; very common when assembling, the fabricator pulls the seam apart...>
The second picture (0690) is of the right front seam. These don’t seem as bad, but since I was already sending the others, I’m sending these as well.
<And this one similar in origin, the panes not pushed together sufficiently after the Silastic was applied>
The obvious question is why not just replace the tank—10 gallon tanks are not expensive.
<Mmm; but/though the size, height of the tank makes these defects okay, tolerable>
The answer is that I’m a salt water enthusiast who has been out of the hobby for the last couple of years since the bottom of my 55 gallon tank catastrophically failed in the night (I emailed you all about it at the time). For the last several years I’ve been studying, learning, gathering better equipment, etc. with a plan to set up a 75 gallon tank FOWLR or soft coral tank later this year. For this reason, I am VERY interested in knowing all I can about whether an aquarium is safe to use, what warning signs to look for, etc.
<I fully suspect it is fine... on the appearance PLUS your stated history/use of this tank. To put this in the first person; I would use this tank>
I’ve read every FAQ regarding silicon seams, but the general understanding that I’ve come to is that an expert eye/opinion is usually needed to make a judgment call. So whether I use this tank or not, my true goal is to see whether it can be used or not. I have a guess, but I want an expert opinion as well.
Again, thank you so much for your patient guidance to all the fish-lovers of the world,
<It is for fellow aquarists, humans as yourself that I/we endeavour. Bob Fenner>


Re: In quest of greater knowledge of silicon seams      2/1/16
Hi Bob,
Thank you so much for the rapid response. My guess was that it was safe as well, but I REALLY appreciate the confirmation.
<Glad to render my opinion; though only partly awake admittedly... this decaf. world will be taking me a bit more time...>
Thanks again,
<Welcome. BobF>

Re: In quest of greater knowledge of silicon seams      2/23/16
Hi Bob,
Here is an update and some new questions. I ended up not using the tank after all. I actually got it set up, but as soon as I did I noticed a chip in the front right bottom corner (see photo 0723). This scared me enough to drain the tank and seek a replacement. I picked up another inexpensive 10 gallon tank. I thought with a brand new tank, I would have no issues. I test filled the tank in my basement, and when I did I saw some weird vertical lines in the seams (see photos).
<Uggh, bunk! How'd this tank get past "quality control?" Return and exchange this one>
In some form or fashion these lines are found in all four seams. It almost looks like the silicon doesn’t go all the way through to the outside.
<I see this; poor craftspersonship>
Also, when you run your finger along the outside of the seam, on most tanks you can feel the silicon sticking out, but on this one you can’t. Of greatest concern are two places near the bottom of the tank where the lines curve to the outside of the tank. I looked through the Silastic FAQs and didn’t see anything that looked like these lines.
The tank doesn’t leak. I tested it for 48 hours (and can test it longer if advisable). The questions are, of course, what are these lines?
<Discontinuities of Silastic, or imperfections in the Silastic itself>
Is the tank safe to use or should I return it?
Should I go back to the original tank, with the chip, or was I right to drain it?
<Better this one than the new one; but I'd ditch both>
I’m sorry to keep pestering you with questions, but I just don’t want another tank disaster. Forgive my “paranoia.”
<Mmm; not paranoid... Or shall I say; maybe we both are!>
Thank you so much for being there and providing your expert guidance to budding aquarists everywhere. We really appreciate it.
<Welcome. Bob Fenner>


Re: In quest of greater knowledge of silicon seams     2/24/16
Hi Bob,
Thanks so much. I will definitely return it. The tank was manufactured by Regent, and the little anchor sticker on the bottom said it was made last month (January, ‘16). It also had the manufacturer’s name, but I’ll “protect the guilty” and not share that.
<Thank you for this input, comment. BobF>

Resealed fish tank and it holds water, but silicone is chunky   12/15/15
Hello, I have searched and searched and can't find an answer to my question anywhere, on any site-
<.... five megs of pix and no reading of WWM?>
so I figured I would ask you. I researched extensively on resealing my 55 gallon fish tank that I haven't had set up in 5 years. I had never worked with silicone before, and put quite a bit on the bottom.

As I was smoothing it out, i realized it wasn't going to be perfect, and wanted extra on the bottom for extra protection. The sides came out lovely, but the bottom is chunky, as i tried to do a few touch up swipes and it's definitely not smooth. I tested the tank out yesterday after 6 days of drying- and filled it 3/4 of the way full on my back porch. The porch was not level

and i was concerned about that being bad for the tank so i emptied it out after a few hours. No leaks! My question is, will the chunky/choppy sections break down sooner than if it was smooth?
<Won't break down in any case>
Is there an increased risk of leaks?
Does anyone really know or should I just reseal it again smooth as butter?
<If you don't mind the look... leave as is>

I am not planning on moving at all- ever again, as my husband and I bought a house. The tank has been through a few moves. I started my first tank when I was 6 years old and am now 32! Now I want my two children to enjoy fish and want my tank to last a long time! Thanks so much. Please see attached photos and let me know your thoughts. I look forward to hearing back from you hopefully soon!~Devlin
<See WWM re Glass Aquariums and Silastic?

Bob Fenner>

Re: Resealed fish tank and it holds water, but silicone is chunky   12/15/15
Thanks Bob for getting back to me so promptly. Sorry for such large photos,
I had no idea they were that big.
I guess when I tried searching your site it just wasn't working out for me with leading me to the forum re Glass Aquariums and Silastic. Very informative though, and thanks for the tip. I will bookmark. Thanks again and have a nice night and holiday season.
<And you Dev. BobF>

Aqueon 40b silicone issue when full.       11/18/15
<James.... 12 megs of pix.... we have a limit>
My name is James and I have been keeping fish now for about 5 years.
Saltwater about 2-3. I finally built my first legitimate reef system. I made the huge mistake of thinking the brand new tank I bought would be fine. I checked the seals visually but never filled it before I began work on it, big mistake. Now I water tested the tank and when I filled it these little air bubbles riddled the seams.
<Yikes... the middle pix.... is the failing area twixt glass to glass; or is it just the area inside/the corner? If the latter, no big deal; if the former, drain this tank>

Can you please check out the pictures and tell me if you think it's ok to use. I have been looking for hours and I read some things about silicone seams on your site. The guy answering the questions seemed super knowledgeable. The 2 pics with the bubbles are full.
The one where it looks fine Is empty. Thank you very much.
<I'd be returning this tank. Bob Fenner>

re: Aqueon 40b silicone issue when full.       11/18/15
Hello Bob,
Thank you so much for the fast reply. The problem is this tank is fully built. Plastic dipped top and bottom 3 holes drilled for the bean animal overflow. 1 for the return.
<.... likely uneconomical to cut away all the Silastic, clean up with blades and solvent, and re-do; BUT, I would NOT use this as an aquarium filled all the way to the top. Perhaps half-filled... Mudskipper? Toxotid? Mangrove biotope?>
The Calfo coast to coast weir is in place and dipped as well. I messed up big time by not testing this tank.
<Ah yes>
It is brand new Aqueon.
<Don't know what I can, should key here.... I have.... regrets re the "consolidation" the aquarium trade has undergone the last 10-15 years.... Like the "Indian Adv." in Kentucky Fried Movie; they've spent money and time... and come up w/ better ads, packaging.... and worse products. TAKE THIS TANK BACK or at least DO NOT use it full. I would be remiss to not be emphatic here.
The bubbles are in the glass to glass seam. It's so weird how they are only there when the tank is full.
<Not all that weird... poor craftsmanship and/or bad product/use
my sump is the same tank purchased at the same time. No signs of this issue. I suspect it is because the sump has center bracing from the baffles. The worst part Is that the bubbles are super small and go the whole way up both seams. Is there anything I can do. I can't afford to buy a new tank, and all the accessories. . I'm thinking my only option would be re doing the front glass. But removing rims can be very hard and I'm not confident I would trust my work to hold up.
<I do understand.... and I would not be re-doing>
I'm so bummed right now because I planned everything so carefully and somehow I missed the most basic step of testing
my tanks.
<Sorry for your trouble. Bob Fenner>
re: Aqueon 40b silicone issue when full.       11/18/15

Hello Bob,
<Big J>
I just noticed the message about the picture size. I apologize about that, I am using a cell phone.
I'm not going to use the tank... maybe I can get it warranted...maybe. I truly appreciate you sharing your time and knowledge with me. I'll have to wait till spring to get this thing re done.
But if reef keeping has taught me anything so far, it's patience.
<Oh yes! The prima facie, numero uno, killer ingredient>
Thanks again,
<Welcome. BobF>

Question about re-sealing a tank that does not leak       11/6/15
<Hi Cherie, Earl here>
I have looked everywhere and cannot find the answer to my question, everything seems to be about resealing tanks that leak.
I purchased an O'Dell 55 gallon tank off of Craigslist in good condition.
Except for some peeling silicone everything looked fine and as far as I know it does not leak.
<Well, the best practice here which I would never consider proceeding without is a simple water-tightness test. Fill it with tapwater, carefully, on some newspapers or butcher paper, being careful not to drip onto the paper. Let it sit a few days. You will know if there is any leakage, and where that leakage is coming from with certainty. I do want to ask, "why reseal it at all if you don't know whether it leaks to begin with?" Test first, 'measure twice, cut once', as it were.>
I decided on scraping off the old silicone and redoing it, but after scrapping all of it off I realized that there was a small gap filled with silicone between the back and bottom panes of glass and both sides, this gap runs the length of the tank. My question, since the tank is not leaking would it be alright to just re-silicone the tank without gauging out the silicone in the gap. I don't know if this was how O'Dell tanks were originally made and I can't find anything about these tanks except that they were supposedly top notch when they first came out.
<I have never heard of this brand but IMO there is really not that much to worry over; given quality materials, a glass box is a glass box...a lot of people make their own. It's not as daunting as it sounds to fix one up.
Remove what silicone you can. The key thing, and the reason you don't just silicone over the old stuff (which might seem logical enough) is that silicone simply doesn't adhere well to old cured silicone. Be sure you are using aquarium-purpose silicone, and follow the directions above regarding testing your seal. If you can do it in a garage or unfinished basement
rather than your living room obviously that's the way to go hehe.>
From inspecting the tank it looks like the gap full of silicone is due to the glass supports at the bottom of the tank that are covered by the bottom trim.
<Glass supports?>
A little more about the silicone in between the gaps: this silicone is clear while the layer of silicone I peeled off was blue. The tank had never been resealed until now.
<Clear stuff may be more "structural" as opposed to watertight. The stuff actually bonding the panels together is not necessarily the same stuff waterproofing the tank, leave it be.>
I really don't want to have to gauge the silicone in the gap out because this is my first time resealing a tank and I don't want to ruin it, aka, causing a tank that doesn't leak to leak.
<I'd leave this alone.>
Thank you for any advice you can give. I really want this tank to work out, but I feel uncomfortable taking it apart, and getting it resealed professionally would cost double what I paid for it.
<Also skim through here http://www.wetwebmedia.com/glstksilastic.htm.  WWM has quite a lot of info on resealing tanks but IMO it's one of those things that's simple yet "scary"...sounds more scary than it is. Just go for it and test as per above. Please report back with your results...hope this helps.>
Re: Question about re-sealing a tank that does not leak      11/7/15

Thank you for the quick response. The reason I scraped the silicone off was because when I got the tank the silicone was peeling and thinning, and on one side there was no silicone, plus there was just too much black mold for my comfort.
<Makes sense.>
I filled it with water when I first got it and didn't see anything obvious, but i should have let it sit longer to be sure.
<A couple days should be fine.>
I don't know if there actually glass supports, it's just what was underneath the bottom trim when I took it off.
I will update with results and pictures when I finish with the tank.
<Please do so :) >

Bubbles In Silicone Seam      10/19/15
Got a 40 gallon breeder from PetSmart. "Great Choice" tank....
<If you say so. What's in a name.... henceforth address me as "Bob-o, King o fish">
The front right seam seems a little sketchy... this is about the bottom 40%
of the front... rest of tank is okay.
<Yikes; poor>
Is this a concern? I was planning on using GE SCS 1200 black silicone overtop on the inside of the tank, reaching further out onto the glass.
<Can't be done to improvement... without dismantling, cutting away the existing; using solvent....>
<Yes; a concern... I'd return this one for another. Bob Fenner>

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