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FAQs on Glass Aquarium Repair, Silicone/Silastic... 100% ONLY, Epoxies... 1

Related Articles: Aquarium Repair, Acrylic Aquarium RepairCleaning AquariumsMarine Tanks, Stands and CoversUsed Gear for Marine Systems, Designer Marine tanks, stands and covers

Related FAQs: Silicone/Sealant 2, Silicone/Sealant 3, Silicone/Sealant 4, Silicone/Sealant 5, Silicone/Sealant 6,& Glass Aquarium Repair 1, Glass Aquarium Repair 2, G lass 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 RepairUsed Aquarium Gear

For repairs... lots of new single-edge razor blades... Likely a holder tool for same... Careful removal of old Silastic... laying in of a uniform bead, smoothing with a tool/popsicle stick/tongue depressor... allowing to cure, trimming off excess... Testing.

Silicon<e> and dying fish??? 12/28/10
I was reading about artificial plants on the net. There is this site that describes using silicone as a base for fake plants. My husband went and used GE silicone II as a plant base and put the plant in. The tube said
that the stuff was not "aquarium safe" My husband then said that meant it wasn't safe to seal an aquarium with and the manufacturer does not want a lawsuit if a huge tank explodes from the wrong silicone.
Anyway, the plant was in there all night and the fish were acting weird this morning. One was hanging out under the filter, the other two were acting normal. I checked on line and found out that this silicone is toxic
to fish, so I removed the plant and did about a 90% water change and replaced the salt. The three mollies are just hanging out now, but that may be the stress from the huge water change. Anyway would Epsom salts help or do I just wait to see if it is too late. I will no longer let my spouse
make any aquarium decisions again. Thank you!!!
<Greetings. Yes, it is true that you need to use only aquarium-safe silicone around fish. The silicone itself isn't toxic so far as I know, but the anti-fungus chemicals added to the silicone usually are toxic, and the
aquarium-safe silicone lacks these. Removing the silicone from the tank, and then doing one or more large water changes, should bring things back down to normal. The addition of fresh carbon to the filter would also be very helpful. After a week, remove that carbon and throw it away. Cheers, Neale.>
<<RMF would like to try correcting misstatements I have made re the use of various "Silicone" formulations... They are NOT necessarily toxic, but often unsuitable in other ways. Please see the discussion here: http://www.gtaaquaria.com/forum/showthread.php?p=107998
Mea culpa, but I have misunderstood that 100% Silicone on labels was and is NOT the same product/formulation. ONLY ones distinctly labeled FOR AQUARIUM USE should be employed for such>>
Re: Silicon and dying fish???   12/29/10

I was e-mailing yesterday about a fake plant with a silicon base, that was toxic to fish. I mentioned I removed the plant and did two water changes yesterday that replaced about 90% of the water each time. Two of the three mollies are back to normal this morning, but one is at the bottom and will not come to the top even for food. She is just there. The other two mollies are adult size. I got this smaller molly in a tank with a group of adults and the guy at the store said she is either a baby or a runt. Anyway it doesn't look like she will make it. My question is: Is the fish suffering??
In that case is it better to put it too sleep or should I wait until she passes on her own??? Thank you!!
<Only you can tell if the fish is suffering. But yes, if she's doomed, there's no point waiting. Do read here:
The ice method mentioned in old aquarium books isn't humane, but the clove oil method is, and 30 drops in a litre of aquarium water quickly sedates and then kills suffering fish. I highly recommend this method because it's safe, cheap and reliable. Drug stores sell clove oil, sometimes as Eugenol.
Cheers, Neale.>

Questionable Tank Seam/Packing Material Left On The Stand -- 06/06/07 Hi, <<Howdy Steve>> I really enjoy the website. <<Thanks'¦me too!>> I've recently purchased a new 115-gal aquarium and after letting it sit for two weeks to make sure it was fully cured I test filled. <<I see>> No leaks were evident, but I do have a suspect seam. <<Uh-oh>> When empty all seams are clear and look acceptable. When filled however, one seam has a fairly large white area that extends approximately 8mm into the 12mm glass thickness for about 12" of the seam. <<Mmm'¦>> I'll attach a few pics to clarify. <<I see these... I'll ask Bob to interject if he feels differently, but it certainly looks to me like you may have an issue with the seal'¦especially considering this only shows when the tank is full of water>> Of course my main concern is that it could be a void in the silicone that may eventually lead to a failure at the seam. <<Agreed>> I contacted both the manufacturer and the store I purchased it from and they both said if it isn't leaking now its fine. <<Bunk'¦>> After expressing concern about the issue they finally agreed that the seam could be redone in the store, but acted like I was being unreasonable. <<Mmm, a shame>> I'm not sure I'm comfortable with an in-store quick fix that they don't believe is even necessary in the first place. <<I'm with you on this'¦perhaps you can send these pics to the manufacturer for their edification and press this issue with them>> I also had a question on the stand. <<Okay>> It's designed to only support the ends of the tank and is actually raised 1/8" on each end so that the aquarium doesn't touch the stand at all in the middle. <<This is not right'¦I suspect there is something amiss with the stand>> The entire aquarium is supported by 2" on either end. <<Ah yes, I see this in the photos. This looks to be a bit of 'hardboard' material'¦perhaps leftovers from the shipping/packing material. Do see if you can remove this>> I've heard about large aquariums being supported mainly in the corners, but never seen it taken to the extreme of having the free floating center section. <<This glass tank needs to be supported along its 'entire perimeter'>> I really appreciate your help and advice. I'm just afraid if I flood the house and ruin our floors my wife will be forever against having another large aquarium. <<Mmm'¦that sounds familiar'¦>> I do understand how she feels, but the fish need room to roam. <<Much agreed'¦and you do have some issues to reconcile re this tank and stand before you can proceed any further>> Thanks, Steve <<Hope I've been of help. EricR>>

Re: Questionable Tank Seam/Packing Material Left On The Stand -- 06/07/07 Thanks for the prompt reply Eric. <<You're welcome Steve>> Both the store and tank manufacturer were adamant that the wood strips on the ends are in fact part of the design. <<You spoke with the manufacturer yourself?>> Their explanation was that it prevents pressure points on the long side that can lead to failure on larger, taller tanks. <<Mmm, not if the stand is flat and planar...as it should be. I have never before seen nor heard of supporting a glass tank 'only by the ends'... So this manufacturer states this tank is meant to hold water; with no support from the stand other than the two-inch wide strip across each end, by the strength of the bottom glass panel and silicone seal alone?!>> The store further said that the tank is designed to be loaded on the corners. <<...! >> They've been making tanks for over 30 years, but it certainly seems odd. <<To me as well>> Do any other manufacturers make stands that only support the ends of the tank? <<None 'I' am aware of...Bob?>> I got a call back from the LFS today, and they spoke to the owner of the aquarium company. He reassured me that the white streak in the seam would not be a problem. <<It is not my intent to cast dispersions on your LFS, but were this my tank/stand, I would want to talk to the manufacturer myself>> My Oscars are rapidly out growing their current tank, and I need to find some resolution to these issues. Now I'm more concerned about the stand than the seam. <<I'm racking my brain but can't recall a similar situation in 'my' more than 30 years in the hobby, but I will ask that Bob add his comments/opinions here (do check the daily FAQs). His exposure in the hobby/trade is much broader than mine, perhaps he can either allay or confirm your (and my) fears re this setup. Regards, EricR>>

Need Your Wisdom/Experience -- 06/07/07 Hi Bob, I've made two replies to a query with the title "Aquarium Seam" in the 'sent' folder that I would appreciate if you could review and add your thoughts. The Chap who wrote in has a tank that has what appears to be a void in a seam that only "shows" when water is added to the tank. <Yikes... this very often is evidence of a poorly made seam, and a small air gap... that gets much larger with vacuum...> But the real puzzler (for me) is the tank's stand. The stand "only" supports the 115-gallon glass tank for about two-inches at "each end." Supposedly, the manufacturer and store owner through which the tank was purchased, are adamant this is how the setup was designed to be used. Is this feasible/practical in the long term? <Mmmm, is... IF the stand is otherwise (very) strong, planar and level... HOWEVER if it is not so in any of these three ways AND/OR some challenge (a big bump, earthquake, floor settling...) occur, can be HUGE trouble. In actuality on the rim/edge of most tanks "touch" the stand... and this touching area is all that needs to be Strong, Planar, Level... BUT there being "more" to the stand provides the stability and strength to this  setting-edge area...> I'm much interested in your take on this. Many thanks, Eric <Will do. BobF>
Re: Need Your Wisdom/Experience -- 06/07/07 Hi Bob, I've made two replies to a query with the title "Aquarium Seam" in the 'sent' folder that I would appreciate if you could review and add your thoughts. The Chap who wrote in has a tank that has what appears to be a void in a seam that only "shows" when water is added to the tank. <Yikes... this very often is evidence of a poorly made seam, and a small air gap... that gets much larger with vacuum...> But the real puzzler (for me) is the tank's stand. The stand "only" supports the 115-gallon glass tank for about two-inches at "each end." Supposedly, the manufacturer and store owner through which the tank was purchased, are adamant this is how the setup was designed to be used. Is this feasible/practical in the long term? <Mmmm, is... IF the stand is otherwise (very) strong, planar and level... HOWEVER if it is not so in any of these three ways AND/OR some challenge (a big bump, earthquake, floor settling...) occur, can be HUGE trouble. In actuality on the rim/edge of most tanks "touch" the stand... <<This I understand...but I have always thought the tank "needed" to be supported around/along the "entire perimeter." Eric>> >Yikes! I see this statement now... A BIG NO to this proposal... Had mis-read that the entire edge was to be supported. I would NOT fill a container thus supported (only on both ends). BobF< and this touching area is all that needs to be Strong, Planar, Level... BUT there being "more" to the stand provides the stability and strength to this setting-edge area...> I'm much interested in your take on this. Many thanks, Eric
<Will do. BobF>
And now having placed the images... This IS a stand that supports all edges... and for the stand-only sakes will likely be fine. HOWEVER, I would NOT fill or keep this tank with the apparent seam problem... Too likely to "pop". BobF
Re: Aquarium Seam, Stand - 6/7/07 Thanks so much for your input Bob. The stand certainly appears to be a conventional "full perimeter" style, but there are two thin strips of wood(1/8" x 3" x 19") at each end that actually elevate the tank 1/8" above the stand itself and provide the sole support for the tank. I made yet another call to the manufacturer today, and once again they confirmed that it was in fact the way they intended the tank and stand to be configured. Another interesting note is that the back of the tank has no center support along the entire 50" length, further suggesting that it was in fact designed to support the tank in this manor. The store specifically told me not to add a center support! I'll attach a pic of the end strips to clarify. <I see this... and do NOT like what I see... There is certainly (daily...) items I am unfamiliar with... but this has me stymied... I REALLY am concerned re this design... And am requesting that you get contact info. re the actual manufacturer of this stand, contact them and/or pass on to me for my contacting them... and GET express warrantee re this stand... On an entirely separate issue: I personally would NOT fill this tank period... until I had the FULL assurance of someone with structural engineering's okay... and would NOT keep this particular tank nor fill it for fear of catastrophic seam failure. The images previously sent show a VERY DANGEROUS gapping in the Silastic. Bob Fenner>

Question about an old aquarium, glass sealant repair?    5/14/07 Howdy! I was recently given a 80 gallon O'Dell glass aquarium by a generous individual. The story with this tank is that its over 3 decades old (33 to be exact). Its built pretty thick and it has very few scratches.  About 12mm thick, green glass on all panels, and support with 4 piece plastic moldings on top and bottom. The seals, however, might need some work. I plan on making this tank a reef tank, but I wanted to get an expert opinion before diving into it. Should the tank be ok to use? I've heard some folks mention that glass may become brittle over time. Thanks in advance! You guys rock! -Vic <Was the tank "kept/stored in-doors?"... If so, and the Silicone seals look, feel okay (still semi-soft/flexible) it should be fine. I might test it (outdoors) on the intended stand, with a bit of newspaper underneath (to detect small leaks)... a day or two ahead of filling it indoors. Bob Fenner>

Algae in my fish tanks seems... Glass aq. repair     5/7/07 Hello, <Hi there> I've read through almost everything on your sight, <site> and other places and am now just confused on what to do.  It seems to me that every situation is different <In some ways/degrees perhaps> so I can't figure out what to do about mine.  I own a 30 gallon Hex tank that has been moved several times in the past year and I am about to move it again.  It has algae growing under the sealant and wishing it away did not work.  At first I thought I would reseal it but I do not want to risk losing my tank completely by removing the sealant to reseal it (that is necessary right?). <Mmm, no> I got bold and used a soft bristle tooth brush to remove some algae and where the algae is gone (though i was careful not to just lift it all up) the sealant is not sticking to the glass. <Well... the sealant in the "corners" is not that functional (that twixt the glass fronts is...), but I would not remove, scrape too much here> Is there anyway I could just remove all of the algae and stick the sealer back on?? <No...> My other thought was sealing it from the outside? <Not worthwhile> Currently where the glass panels meet there is a small gap on the outside, and it is sealed on the inside with 1/4 to 1/2 inch of flat silicone (I'm guessing) coming off to the sides and it is the silicone off to the sides that the algae has destroyed.  What do I do? Any advice is greatly appreciated. Vanessa C. <It is unusual that algae has gotten to growing inside the sealant as you state... I do encourage you to consider cutting out all the inside sealant with this next move (when it's convenient) and replacing it then... Please read here re: http://www.wetwebmedia.com/glstksilastic.htm Bob Fenner>

90Gal Repair....  4/17/04 Hey I have read all the pages of your FAQ <Doubtful> and I still have a few questions left unanswered: The story is my friend is starting getting into the hobby of caring fro fish! <Ones with bushy hair-dos?> He is very excited and likes to do things the right way. We started with a small 40gl tank and now he bought a used 90gal with leaks. We are attempting to re-seal his tank, and have already scraped the bottom edge. <Need to "scrape" remove all the inside Silastic... clean up the areas with single edged razor blades, a solvent...> After reading through the FAQ I am convinced that we need to scrap the rest of the silicon off, that should be no problem.  A flag that arouse is: Should we take the entire tank apart? <I would not> or do think it would be sufficient to re-seal the tank from the inside only?   <Should be> If you advise us to take it apart how do we remove the plastic caps on the bottom and the top of the tank with out breaking them? <I would leave the frame/moulding in place...> Are the solvents mentioned in the FAQ's safe to use on plastic? Will they just melt the silicon away? <Mostly the latter if applied "correctly"... I'd keep the rags, what have you with the solvent away from the plastic...> Or do we need to wipe the silicon off with the solvents in place? Thanks, Ozzy <...? Don't follow you here> PS- Great site keep up the good work. <Please read what you think you're writing to someone, amend before sending. Bob Fenner>

Please Help with Tank seals!!!  -- 4/9/07 To Robert, I am not a manufacturer of tanks so some of the finer points elude me I hope you can assist me. I was wondering if you could inform me as to the common or uncommonness of air bubbles stuck inside the silicone seals of a tank with large seals the tank is 96x45x24. <Not uncommon...> I have a few bubbles in the seal, mostly on the bottom some more than 1/4 of an inch, <... I don't like them this large...> when I attempted to fill the tank the bubbles stretched on the outside panel <!> in the seal almost coming up to the gravel at the bottom of the tank I had it 3/4 of the way full the bubble was almost 3 in long (the seals are almost 4 in long and triple paned at the edges for seal), <?...> I had emptied it rapidly and the bubbles shrank back to mostly normal I believe the bubbles are now more apparent and possibly even a few more than to begin with. Any Ideas? <From the dimensions, I take it this is a custom job... by a large manufacturer? Triple paned?> Does this make it unstable? <Mmm, unable to say... wish I was sure that whoever made this tank had seen, has seen this/these defect/s...> I just want a few outside professional opinions as to this situation/condition. I am talking to the manufacturer as well, <Ah, good> as a side note this is the second tank, the first one we got had faulty seals to the point it exploded in the office. <Yeeikes!!!> All the info I have about the manufactures is good stuff great looking tanks and from speaking with them very knowledgeable, the owner has been making tanks 18 yrs. They are investigating the problem and likely to recommend the re-fill of the tank, I cannot have another tragedy happen as it would likely ruin me/ destroy my confidence in glass tank manufacturers all together. <Mmm... would you please send some images of these air gaps... with the tank empty, filled... not changing the settings of the camera, or its distance from the work?> P.S. I love your book read it years ago, recommended it to hundreds of people as a great no-nonsense read. Thank you for your time,
<Welcome. Bob Fenner>
Re: Please Help with Tank seals!!!  -- 4/9/07 here are some of the pics of the seals.  there is a shadow above some of the bubbles in the pics, the shadow is the growth from filling. thanks, Dan <Good pix... from what I see these bubbles shouldn't be a problem going forward here... May seem not to matter, but I would place some sort of visual barrier (even just stout tape) around the base here... to "take your mind off" these defects... But there seems to be sufficient seal area for this depth/configuration of system. Bob Fenner>
Re: Please Help with Tank seals!!!  -- 4/9/07 hi Robert, thank you for your quick response. it is very reassuring. I've just heard back from the manufacturer, and from the photos they feel that a section of the seal is wet. and want me to remove all the gravel and decor, to allow it to dry for one week. do you feel removal of the gravel/ decor will make a difference? <Yes... if this "wetness" is/was the matter> as a side note, the manufacturer took three months to replace/ send the tank and one week for shipping. your thoughts would be greatly appreciated. <... So... when in this time frame was this tank/glass assembled? If more than a week or so... the Silastic/Silicone should not be "wet"... Am dubious. BobF> Thanks a Million,
The Aquatic Doctor
tank seals????  -- 4/9/07 hi Robert, <Doc> so I gave copies of the emails, regarding the seals, to my clients and they would like a "tank expert" to come out and look at it. after I had explained who you were and why I was trusting your opinion, they told me they wanted me to get YOU out here to look at it and that they are more than willing to pay you. so they wanted me to ask you to come out and take a look. I'm asking, would you be willing to come out and take a look? <Heeeee! I do work in the trade/interest as a consultant... but am out in HI, and my time is pretty much committed in to 08...> if not I understand. and I have been instructed by my clients, to fill the tank tonight, because they believe if it does go wrong it is just shoddy craftsmanship. thank you so much for all of your help, daN <I do agree with the gist of your customers sentiment... I do understand the rationale behind some fabricators building multiple glass panel bottoms, not joining the sides, front and back directly (down) onto the bottom... but don't agree with this methodology... for obvious reasons... a small strip (a couple of inches) can be fashioned, adhered into the joints with silastic... with as much added strength as the current design... w/o all the weight added, or concerns with Silastic curing. BobF> Thank you your Business is Appreciated! Daniel
Re: tank seals????, consultancy  -- 4/9/07 Hello Robert, I am sorry about the spelling, its been a long day. I assumed you were busy, do you happen to be able to recommend someone around or near Pasadena C.A. that has extensive knowledge of tank construction and curing. I tried pushing on the pane of glass something about the bubble in the middle of the front seal seemed wrong, and sure enough I was able to 'float' the bubble between two and a half panels of glass. <Mmm, yes... first try, a friend in the trade, Jim Stime... am Bcc'g him here> The seal is definitely still wet deep inside near the bottom, I think the top pane closest to the gravel is cured as the seal is a different color than the bottom seal. <Mmm, well, the closer the Silastic is to an edge... where it will, would come in contact with air...> My clients are mad and of course blame me for recommending the manufacturer. I am trying to resolve this as soon as possible I am trying to find out what kind of silicone mix they used in construction. <... an interesting comment... Should NOT be a mix...> Any help you can give would be greatly appreciated. It is an honor to talk to you. <There is much to state, speculate... too much for this mechanism of writing back/forth in the short term> P.S. Thank you again for your quick responses, I know its getting late must be a great view from HI <Ah, yes... Jim? You can see the pix et al. Daniel has sent along on WWM's Dailies today. Bob Fenner> Daniel The Aquatic Doctor

Re: tank seals????, consultancy   4/11/07 Hi Daniel and Bob, <Jim!> Thank you for the vote of confidence Bob, and sorry to hear about the bad experiences with your glass tank manufacture Daniel. Is this that glass tank company out of Canada ? To be quite honest my experiences have been 98% with acrylic tanks and very little with glass. Based on what I can gather from the e-mails and the pics posted on WWM I can see the bubbles in the silicone ( damn that's thick silicone seams ) and it sounds like the tank manufacture wishes to allow the silicone to dry for a longer period of time, and yet the customer wants to fill the tank ? Tough spot to be in. personally I think one needs to lean towards the safety aspects of this situation and abide by the manufactures recommendations. If one is looking for a Tank Expert then one should call upon a tank manufacture. My tank manufacture, Clear-For-Life, does both acrylic and glass.  I do not believe he does glass tanks over 300 gallons and since he has limited the size he manufactures calling upon him would not really help. Truth is anyone other than your manufacture is potentially being saddled with the liability of this tank and its seal. I really think this is the responsibility of whoever made the tank and you need to get them to state their recommendations in writing. Follow their suggestions and If there becomes an issue then at least you have a written acknowledgement and confirmation of the problem and their solution. If your customer is pushing you to fill it and you are at all uncomfortable with that then get them to sign a piece of paper stating they wanted you to fill it. Remember, if something goes wrong YOU are responsible and liable. This is a business and its all about doing the right thing... and  covering your ass. Sorry I don't have any better suggestions. Feel free to call if you wish, 805-241-7140. <Mmm, am going to tentatively leave your phone number here Jim... as I do believe this is likely your intent, and that folks could find it easily from your many web-business links... Cheers, and thank you, Bob Fenner> jim Stime, Jr. Resplendent Group Aquarium Design www.aquarium-design.com MyFishTank.com www.myfishtank.com Midwater Systems www.jelliquarium.com Centropyge.Net www.centropyge.net MACNA X www.masla.com/macnax.html

Re: tank seals????, consultancy  -- 04/11/07 Hi Jim and Bob, I thank you both for your expertise and advice, my clients were trying to push me to fill it no matter what! (frustrating), I was already thinking along the lines you suggested, and after having confirmation of wet/liquid silicone ( visible when pressure was applied to the glass). I am following the manufactures direction (at their expense) <... this Silastic won't cure here... for years... in the absence of oxygen, it's as if the product were still "in the tube". RMF>  I have emptied 300lbs of gravel and 400lbs of decorative rock and the tank is sitting empty bone dry with a small space heater on a timer to keep the temperature stable at night. The manufacturer is from the eastern U.S.A. Everything I can find out about them is good, and they have backed their current product to the extent of saying the seal should last 25 years. If everything goes well It should be good to go in two weeks. Thank you again for taking the time to communicate with me. I love glass tanks but this has been an expensive headache, maybe scratch removal in acrylic is not as tedious after all. Thanks a million! Daniel
The Aquatic Doctor

New Tank Seal Problems  4/8/07 Hi  Crew; <Jeff> I have been planning on a major upgrade for over a year.  I ordered a custom 54" x 30" x 30" glass aquarium and this weekend I  finally  set up the tank!! <Looks like a real project!> It is completely level, on 2 times 3/4" plywood.  There are 2 x 6 cross supports every 12" and I put a 1/2" rubber pad under the tank.  I couldn't find any Plasti-Span locally and all the foam insulation I could find was too compressible.  The rubber pad is solid and flat.. no ridges or anything, but it does compress enough to ensure a solid even floor for the tank and no stress points.. <The stand looks very good, sturdy> I set-up all my bulkheads and stubbed out my piping to shut-off valves so I could fill it. On Friday night (April 6th) I filled it for the first time.  No leaks anywhere.  But as it was filling I noticed an odd discolouration develop on one of the joints.  I have attached a pic of it.   It is the one titled "2007_0407Image0009c3.jpg" <I see this> The spot has not grown in the past  36  hours (I am writing this  Sunday Afternoon).  I also notice some white streaks in the other joints.. but I believe they are not in the Butt joint themselves.. rather it seems these other spots (More like vertical streaks) are where the bead has been applied in the corner. <Yes... these are not a problem> Is this spot I am worried about normal? <Mmm, no> Is it only this noticeable because it is black silicone as opposed to clear? <Perhaps> Should I be worried? <I am> How long should I test for leaks? <Mmm... a week or so... however, if you continue to evidence "growing of this area"... to the edge of the outside of the tank... I would drain it...> I guess I am trying to ask.. Is the tank ok?? <Not IMO> I would really hate to have 200G of water all over my floor lol.  This may be a crazy question.. but how long can a person expect a Tank's Silicone Joints to hold before worrying about it coming apart?  Would I see a leak develop first? <Hopefully, but given the location, down near the bottom... and size of this growing imperfection, I am concerned that there might be a catastrophic failure here> Or can a panel suffer a catastrophic loss of holding power? <Yes> All I have ever had before were 75G Tanks.. never ever worried about this stuff.. but now that I see 200G of water suspended in the air.. it has freaked me out a bit.. lol <I understand> I also attached some more pics showing the stand construction.  Also, the pic titled "2007_0407Image0001c2.jpg" is another of the spot in question.. but I used a flash and the whiteness looks a lot more spread under the flash than what is really going on. Please let me know what I am facing here. Thanks! Jeffrey T. Reath B.Sc. <Mmm... over the years there have been spates of "bad runs of Silastic" that have yielded/resembled the defect/s shown. I would definitely have the dealer come out, look at the tank... render their opinion (in writing) re... and be prepared in the next week or two to drain... Bob Fenner>

Re: New Tank Seal Problems  4/17/04 Hi Crew (Robert); <Jeff> As an update to the issue I e-mailed about before: <Ah, good> I talked to the manufacturer and we tried a different pad under the tank and verified the level of the tank in all directions and diagonally.  There was a feeling that it may have been a stress point. <Mmm, a possible contributing factor... but no> However, nothing made the mark any less and the feeling was that the mark should have changed when the water was drained and the stress was relieved. <Yes... if so...> Over the course of a week the mark slowly faded, BUT the seam itself became less opaque.. To the point that I could see through the Butt joint to the opposite edge of the back panel.  This should not have been the case with Black silicone.  The tank has been taken down and sent back to the manufacturer for repair.  In their opinion and the opinion of the Silicone Maker (GE) it was probably an incorrect clamping procedure during the application of the silicone in the first place. <Yes... this or insufficient material applied...> It resulted in too little silicone that was stretched beyond tolerances once the tank was filled. I am just passing it on in the event it comes in useful in another situation. Thanks all. Jeffrey T. Reath B.Sc. <Thank you for this follow-up. Bob Fenner>

Silastic bead input   3/4/06 This is a follow up to a reader post on his construction of a 300 gallon glass tank with MDF base with fiber glass sheathing. Re: Tank Fabrication   3/3/06 . This is my third posting in a week (I will try not to make a habit of this). I thought my experience may be of some interest and help. <Thank you for this> The reader had some trouble with bubbles in the seams. I have seen this in a lot of tanks. Most of the time you can get away with that as silicon holds 300 lbs per square inch. Common practice is just to fit the glass edges together in a similar fashion to working with wood or acrylic. This results in a silicone seal that is not thick enough, and the risk of bubble formation later. I read the directions on a tube of silicone sealant ( Silaflex RTV), and it states'¦ Extrude sealant into joint. Minimum joint size 5 mm wide x 5 mm deep and maximum joint size 25 mm wide x 10 mm deep One of the glass and window suppliers here in town went on a conference and one of the topics was how to silicone glass together. He was told the depth of the seam should be about half the thickness of the glass. So a 10 mm glass should have a 5 mm deep seal. This offers a stronger and more flexible seal, and less chance of bubbles. I have built about 3 all glass and 3 glass/plywood tanks and I have never got any bubbles in the seals doing it this way. Vertical glass panels can be held in place when gluing by cross bracing the corners with strips plywood that has two sided foam adhesive tape on it, and simply pressing them on the top edges, and easily removed later. Commonly the side panels of the glass are laid on top of the glass base. It may be a better approach to lay the vertical glass panels around the base and allow for a large seal around the edge. I always pay extra to have the glass flat polished with smooth bevels on the edges. It is safer to work with, and I think essential on tempered glass, as a chip in an edge can cause the panel to explode. Have Fun Mike Lomb <Thank you for this Mike. We have some trouble with some "tray less" queries (yours here is one) that don't have email addresses to respond to... but am hopeful you will find this posted in the dailies, and that others will benefit from your input passed on. Bob Fenner> Silicone peeling, air bubbles and pin hole leak  - 02/27/06 HI Bob and crew.  I love your site and I am amazed on how many questions you answer in the FAQ section of tank repair.  After reading the posted FAQ's, I am still unsure what to do.  I have a hex 53gal(?) 48"Wx12"Dx21"H  that was my favorite LFS's display tank I bought 10 years ago when they went (sadly) out of business.  This tank has moved with me three times, the last move resulted in this tank's storage for 5 years. I was thrilled to move into a new pad last month that allowed me to have my prize tank in the living room.  Today, I set up, leveled and filled my tank looking closely for leaks. <Good move>   After three hours I noticed a drip that would pop out from one of the vertical front seams 2/3 the way to the top of the tank every 5 or so seconds.  Not a stream, but a drip.  After closer inspection I noticed on the inside of the tank there was a bubble of what looked like a badly applied seam of silicone that I must have burst when I rubbed down the tank before filling.   <Maybe... Silastic does get a bit dry, brittle over time...> I am guessing that when the tank was built, there were air bubbles in the silicone and finally the "one" was broken allowing water to seek it's way out. <Yes, likely so>         While the tank was full, I pressed inward on the front panel and found very little deflection at the seam as compared to the opposite side.  After draining the tank, I pressed inward on the panel and found the amount of deflection in the panel the same as when the tank was full. I am guessing the structure of the tank is OK and it wasn't ready to burst and give the front section out.  However, in a 8" section there are many (about 20) small air bubbles in the silicone between the front panel and the LH 45 degree panel midway on the vertical plane.  Also, the silicone has peeled back in three other spots at other vertical joints, most likely caused by my aggressive blue lobster or crayfish that I had in the past, but these other three areas do not leak and the silicone appears to be solid between the panels. <This is very good news> Should I attempt resealing the tank? <Yes, I would... this time, not cutting all the Silicone out... as between the glass to glass faces, but carefully removing all the beads at the junctures...> And if I do reseal the tank, should I dig out the air bubble laden 8" section or just reseal over this area? <I would not touch the between glass areas unless you intend to take ALL apart and re-do> I would really like to save this tank and use it as an aquarium.  Since this tank is over 15 years old and I have no idea of the brand, getting a replacement tank that would fit the stand and cover is unlikely, resulting in a totally new setup.     <Such dimensions tend to be very conservative... could likely find a tank of similar bottom size>         I tried to take pictures of the air bubbles, but it is difficult to get the digital camera to focus on these bubbles.  Thank you for your time, Mike <Take your time here Mike... lots of new single edged razor blades. careful cutting away, using your hand to block cutting into the area between the glass panels, while holding the blades... Bob Fenner>

Re: Silicone peeling, air bubbles and pin hole leak - 2/28/2006 Thank you for responding so quickly!!!  I will reseal the tank, hopefully this week.  I will follow up with you with (hopefully) a good success story.  Thank you again, Mike <Real good Mike... not hard to do these sorts of repairs... some eye-hand coordination, a couple of tools, and mainly: Patience. Cheers, BobF>

Pulling An Aquarium Out Of Storage    4/4/06 Hi crew, I was browsing your site, but didn't find quite the answer I need... I have just pulled my things out of storage, including a 29 gallon aquarium.  It has been stored for 2 years (nicely wrapped and crated by professionals). My question is this...should I be concerned about the quality of the seal?  Is there a way I can test it without filling the whole thing? It was only about 2 years old when it went into storage. Thanks! Jill < Usually aquariums placed in direct sun and stored outdoors are the ones that are the biggest risk. Push on the silicon seal in the corners. It should still feel spongy with some push. As long as it is not hard I would think it is OK. I would still fill it up to double check.-Chuck>

Removing fish during silicone curing?    5/27/06 I just had a mishap with my 25 gallon aquarium. I hit the corner of the tank about 3" from the top and it chipped the edge and made a crack extending out and up about 3". < That is no fun at all! > The inside corner seal is intact and so far the water just beads up on the outside of the crack. < So far is key here! > I brought the water level down below the crack which I temporarily sealed on the outside of the take with duct tape until I can fix the problem. < You aren't from the south, are you? Around here, we use duct tape for just about everything! > My question is, since the crack is high enough to repair the tank without draining it completely do I have to remove the plants, angel fish and crayfish while the silicone cures? < It would be a good idea not to have them in the tank while it cures. > The fish are still small and I was hoping to wait till Christmas to get a larger tank. < That is always a great Christmas present! > Will sealing the crack with silicone give me this extra time or do I just call it an early Christmas? < I would call it a much warranted early Christmas present. > I know 100% silicone is safe for fish after it's cured, but I can't find any info about during the curing process. < The fumes given off are fairly toxic while curing. It is better to err on the side of caution! > Thanks for your help. < You are very welcome! > Sue < RichardB > Big Mistake...How do I fix it? 100% Silicone, Toxic systems   6/13/06 I hate to bother you as I know you guys are busy helping people with real problems that can be solved but here goes anyway. I had a very badly designed sump setup (wet/dry u-tubed to a 10 gallon refugium u-tubed to a 10 gallon sump) <Yikes... U-tubes are not to be trusted...> that I tore down hoping to build something similar (no u-tubes, entirely in a 55) using the EPDM baffling I read about here. Well, after setting it up with the EPDM, I realized that the baffles were not going to stay in place, water pushing them over. I quickly used GE Silicone II to silicone the baffles into place. (I did not notice until way too late that it says "not for use on aquariums"). <Yikes... want to avoid types with "Mildewcides", other additives... Use only 100%...>   I also only let it dry for about 12 hours. <Needs 24...> I have removed the sump completely while I allow the new silicone to cure. I performed about a 50% water change. All of my fish seem to be O.K. I have no filtration at all while the silicone is curing.  So, since I have lost every SPS in my tank and all of my soft corals look terrible and my 10-12" anemone has shriveled up to about 2" I was wondering what you think I should do to help alleviate the problems and get my tank ready to house corals again? <... if it were me/mine, I'd cut away all the present Silicone and re-do this with 100%... Or, buy a new sump...> How long should I wait before trying to add any corals again? Thanking you in advance for the extreme wealth of knowledge you provide to me and many other people with this aquarium obsession. <Do take the long view here... You don't want to have mal-lingering dread re toxicity issues... cut out this "door/window" Silastic and replace it. Bob Fenner>

Large Tank Questions and Outcome of Silicone II  5/29/06 Hey guys, wanted to bounce a few plywood tank questions off of ya and provide experience input concerning Silicone II. First things first, I have two large tanks which I recently set back up (long story), I used swimming pool paint which worked VERY well and had no adverse effects on SPS or other livestock. Long story short, when I set them back up, I used Silicone II to reseal the corners of the tanks. It has now been 2 months, I am getting consistent trite readings of .025 (Salifert), not high but it should be 0. I am now faced with daunting task of replacing the silicone with Silicone I. (I tried everything including adding live bacteria, carbon, Purigen, all types of stuff, bottom line, at least in my experience is that Silicone II isn't reef safe, live rock is 8 years old) <Yikes...> Now on to the large tank questions. I searched all over, including GARF for info on epoxies. Swimming pool paint with plywood tanks works for several years but ultimately you end up with micro cracks in the paint that need to be patched with silicone or repainted. I am building a tank that would be approximately 1500 gallons, I want to use a reef safe epoxy but I cant locate where to buy Rustoleum or DuPont potable water epoxies, do you guys know of anywhere, or know of any alternative epoxies that might work? <Mmm, I'd look into your local swimming pool supply places here. I have used Nelson/Nelsonite with good results as well as (more pricey) Spar products (intended for the boating industry)> I have also come to the conclusion that since this will be a reef, I am best using glass versus acrylic since acrylic will ultimately get pitted by coralline (I even looked into Polycarbonate but from  what I understand it bows too easily). The glass dimensions would be front panel 96"x30", would 3/4" Starbrite or Starfire glass be thick enough in your experience? <Yes> From what I have read it is reinforced glass, and while pricey, is much stronger As always thanks, Tom <Thank you for sharing Tom. Bob Fenner>

How do I de-contaminate my fish tank after my brother tried to clean the silicone off with petrol ?   8/24/06 Hello Bob ! Please help. I bought a second hand tank and had removed the inside panels as I wanted to install an external filter rather than using the overflow system. Problem is I removed the panels and cut off the excess silicone with a blade. My brother then decided to clean the silicone smudges with a cloth soaked in petrol ! He is not very bright ! Please advise how do I de-contaminate the tank before adding fish ? Please advise ! oh mighty wise one ! Thank you <Wipe with a solvent... Xylene, even Acetone, wash the tank in turn with plenty of water and coarse salt. Bob Fenner> From Denny Moodley, South Africa

Tall, skinny tanks   1/4/07 Hello, thanks for your site- it is very helpful- and I really need help! Here's a new one (please bear with the long story): I am an sculptor.  For about 10 years, I have been making  glass tanks that are tall (up to 6ft) and skinny .  For example - 4" x4"x70  or   7"x3"x 68" at the largest. <Neat... have seen such in years past... there was even a go by a commercial manufacturer to produce, use these in place of a panel of a slider/glass door...> I have been using  1/4" glass <Yikes... not thick enough for much of anything beyond 24-30 inches in height (length, width not as important...)> and GE 100% silicone.   The tanks get filled with a solution of mostly water and a little vinegar.  (According to GE, vinegar is not a solvent for silicone.) <Mmm, not once it is cured, yes...> They stand on the floor or are siliconed to a small glass base.    Some of these pieces are still fine but some have started to leak after 6+ years. <Yes... your initial construction must have been excellent for them to hold together in all honesty>   I think it is because I have been doing these myself and have not been able to achieve a good enough seal when attaching the last side of glass.  Also because they are so tall and skinny, <Yes, this latter> I cannot manage to apply another bead to the inside. <Understood... no room to get tools, the material in> I use a home made tool with a  sanded dowel to smear the last two seams. I have an exhibition that I need to get right.  I want to make tanks that are similar in proportion to the ones above.  I will also find some help in putting them together.  Do you have any recommendations for the construction? <Mmm, no... perhaps to contact Dow-Corning... the biggest patent/technology holder (as far as I'm aware) of Silastics... and ask for their input here> If it is buy a book - which one? <None as far as I know> Should I be using thicker glass?  How do I calculate this? <Mmm... there are "average" given strengths for such... depending on the type of glass for instance... You would do well to contact various "Glass Institutes" and seek their input here... Some laminated glasses, even acrylics and their solvents... might be I was also thinking of siliconing Pyrex angle directly to the column to the make an exterior frame but I have not been able to find a supplier of this material.  I have done it with 3/4" plexi angle as a default but I don't think it would work to stop a leak. <Mmm, no, not advised> Also, another question about silicone- GE recommends a 3/16" thick bead. <The bead itself is of small import... the actual seal strength is 90 plus percent the material twixt the viewing panels/panes. The bead principally exists to prevent cutting into the material between the facing panes> If it is thicker than that when it is squished and used to laminate something like 3/4"  angle to the corners of a tank,  do you think the space is too thick for air to get in and cure the silicone? <Oh... there should be very little... practically as little as possible, Silastic/Silicone in-between... the Silicone to Silicone material is not really what makes the seal...> Thanks so much! Jennifer <Welcome, Bob Fenner>

Silicone Can you tell me which brand of GE Silicone is reef safe? Silicone I, II  window or kitchen and bath? Thanks < Use only the silicon that specifically says on the package for aquarium use!!!! All the others have midewcides that will kill fish.-Chuck> <<ed. note: GE Silicone I has been aquarium safe to date, but II is not.>><<<Common progenitor's note: 100% Silicone will do it... RMF>>>

Pink silicone Hi WWM crew, I've searched Google, my chemistry textbooks, and your website, but I'm not really getting any answers that help me. I have a new-ish tank [about 4 weeks old - 88litres], that is home to three [older] goldfish. Today, when changing the water, I noticed some of the silicone seams were pink. Most noticeably the brace [is that what it's called?] across the top of the back 'wall', on close inspection three of the corner seams are also pink, but not to such a great extent. The brace at the front of the tank is unaffected.  Also, when rinsing the filter [Fluval 2 plus - is as old as the tank] the sponge was an off-red colour. A polyester pad was also in the filter, this was not discoloured. The water is clear. This may be normal, but noticing the pink seams at the same time makes me wonder if they are related?  Due to the tank cycling and huge amount of waste from the fish, I've been changing the water at least weekly, and have never noticed the discolouration before.  I am aware that some products have a pink colour in their sealants, but it is not consistent all along the seam, and has only just appeared.  The fish are not showing any signs of discomfort/illness. All that has been added to the tank is Tetra AquaSafe, Sera Aqutan and Nutrafin Cycle. I feed the fish goldfish flakes once a day, substituted with peas 3 times a week.  I have two older tanks [treated in the exact same way], and have never experienced this - I can't help feeling that something must be reacting [a transition metal?] with the silicone to turn it pink, rather than it being a natural colour change.  Is this something I should be concerned about? Thanks a lot in advance - and keep up the fantastic work!  Kay < Medications and chemicals can be absorbed by the silicon sealant and give it an off color. Foods with a red base and tannins from driftwood may also leach into the water and eventually discolor the silicon too. But what I think you are observing is a reaction to the lighting you are using. The area with the most pink seems to be the area nearest the light bulb so I am going to take a shot that the silicon is having a photo sensitive reaction to the particular light bulb you are using. I don't think it will affect the silicon but I would still routinely check it for elasticity.-Chuck>

Re: Pink silicone Hi, Thanks for the reply. I don't think it is light discolouring the silicone - there is no light bulb in the hood, and the back is next to a wall [so where the pink is, is probably one of the darkest areas in the tank]. The flakes I use do have a red colouring, but this is a fluorescent kind of pink - like someone's run a highlighter along the silicone. Also, there has never been driftwood in the tank, and all ornaments in it have previously been in one of my other tanks with no problems. I'll keep an eye on the integrity of the seams, but I think I can cope for now as it doesn't seem to be affecting the fish. May be worth contacting the manufacturer? Thanks, Kay <With the info you provided , I now think it is from the food. Many color enhancing foods have ingredients that may have an ability to stain things. A diluted solution in the water may also stain the silicon over time. I would recommend changing food for awhile and see if the coloration goes away or at doesn't become worse.-Chuck> 

Toluene, rubbing alcohol and resealing tanks Hello Mr. Fenner,     I am in the process of resealing a leak in one tank and tearing down one other that has a broken panel.  I searched your FAQs on tank repair and found lots of information, but I want to make sure to get all of the silicone out from between the panels on the broken tank.  I saw that you mentioned using toluene to get the last of the silicone off.  Can this be poured into the seams after most of the silicone has been cut away so that the silicone in-between the panels will come lose or should I try getting the razor blade edge in-between the panels? <Mmm, not likely. I have used this and other solvents in actually rubbing the glass panels once they are disassembled... and most of the old Silastic removed via single edged razor blades. I don't think much toluene would get into the between glass area if just poured in> I plan on using the unbroken panels to build a different tank for coral prop. Thanks, Daniel <... Two comments... If you want the cleaner appearing job, you'll want to take the whole aquarium apart and re-do all seams... BUT, maybe you can just adhere a new panel to the outside and inside if you are not going to look much at the tank itself... Bob Fenner>

Inner Silicone seal coming loose Hi gang, <Nate> I'm in the process of cleaning up a 155 gallon bowfront that I bought from the president of the local saltwater aquarium club. It's an awesome tank, and should be much more fun than the current 75 gallon! <Yes... at least twice as much!> As I've been working on cleaning things up and getting ready to install a coast-to-coast overflow,  <?> I've noticed that some areas of the inner seal are pulling loose at the edges. Nothing is completely loose anywhere, and the tank didn't leak a drop (it's only 3 years old...he's moved up to a 240 gallon now) when it was set up at his place. My question is, should I take the opportunity to re-do this inner seal (I've read all 3 pages of the FAQ on this...and know that all that inner liner has to come out...not just where it's pulling loose) now, or is it better to take the approach of "If it ain't broke, don't fix it," on this...since it isn't the main seal material that's between the glass? I've never dealt with glass tanks, always had acrylic until now...so any advice will be much appreciated! Thanks, Nate <This is a tough call... well, let's state the important facts... The only real seal is the bit of silicone between the glass... not the bit above, in the joint/corner... this material is most useful for preventing the jamming of a sharp object (most likely a razor bladed algae scraper) into the actual functional seal/gap... If it were me, mine, I would place the tank on a flat/level/planar surface (on a stand outside that has been shimmed, a good level placed on at all points) and fill the tank... leave it for a day or so... if it doesn't leak, I would NOT fool with it... too likely that the process of cutting away the existing corner material will result in an even less sturdy construct. Bob Fenner>

Re: inner Silicone seal coming loose Thanks for the reply Bob! <Welcome Nate> When I mentioned cleaning up, you responded with a question mark. As mentioned, we bought this from a friend of ours that's moved up in size. I am working on cleaning all the glass surfaces (removing coralline algae build-up and such...general cleaning is all). <Ahh, good... I took this as cleaning up... as in cutting out the existing seal> We will indeed be setting the tank up before moving it inside.  <Good> I'm re-plumbing it, and will need to check the plumbing for leaks, as well as the tank. I was also there when it was drained, and know how it was moved (with me breaking my back on one end of it to get it into the moving van). <Yikes... been there> There was absolutely no leaks in the tank at that time, and it was handled delicately in the moving process. <Good to check again though...> From your response, sounds like I'll be best to leave things alone.  We don't use an razor bladed algae scraper, I've got a hammerhead magnetic tank cleaner, and for the harder to get stuff, I use a plastic hand scraper (as did the previous owner...so I'm guessing the inner seal is pulling loose from having the magnetic cleaner catching the edges is all). <Maybe> You are a great resource for the aspiring hobbyist! Keep up the great work! Nate <Will endeavor to do so my friend. Bob Fenner>

New aquarium repair I just received a 96x30x30 Starphire aquarium from Inter American. The front and side panels are 1/2 inch Starphire the bottom is 3/4 and the back and Euro- bracing is 5/8 regular glass. The problem is that there are hundreds of bubbles in every seam of the aquarium. The bubbles are large some around an inch long. Inter American said that it was normal to have this many bubbles because the glass is tempered <?> and they will not give me a refund. When I fill the tank about halfway the left front seal turns chalk white. <Not good> It first turns chalk white only at the bubbles but then I can see the white areas spreading the longer it sits. They told me to let it sit empty for a few weeks to let the silicone harden more and that everything would be fine. <Umm, the Silicone "hardens"... little... it cures in a day...> I'm guessing they are just lying to me and this problem will not fix itself. The only seam I have seen turn chalk white is the front left but every seam has hundreds of bubbles even the seams of the Euro- bracing. Can I fix this? I do not have any experience with building or fixing aquariums. Thanks <Fixing is difficult... requires cutting out the seals... including between the glass (the only functional seal)... I would be talking with your/their States General Attorneys re the legality of this sale, lack of exchange. Bob Fenner>

Resealing a tank 2/17/03 Hello, <cheers> I hope you can take the time to answer a question for me. I have a 55-gallon tank in which I would like to replace the silicone seal on the four inside vertical edges. <not possible... any resealed tank must have the entire inner seal removed and then resealed fresh- wholly. The reason is that new silicone does not bind/meld with old (cured) silicone. Thus... the point at the bottom seams where you had wanted to stop will be the next place the tank leaks. You also need to lightly sand the interior seems with fine sandpaper (car bodywork for paint/buff) to abrade the silicone stuck in the pores of the glass... else you will have the same problem. Resealing tanks is a lot of work and relatively unreliable. Many leak again within 2 years. For tanks under 100 gallons, I don't recommend it at all> The turtles I keep in the tank tore up the original rubber. I have since put strips of plastic corner-guard in those areas to keep their claws away. I noticed at the local professional tropical fish shop that I might buy a standard sized tube of "All Glass" 100% silicone for about $15.00 US. Q1 Is there any GE or other silicone that you know of that does not have the fungicides in it that would be cheaper than the All Glass material? <there are... but for the extra $ 8-10 I recommend the aquarium made brand for insured safety, tensile strength and peace of mind> I have read that new silicone will not stick to cured silicone. <exactly correct> Q2 Should I cut away the entire old silicone bead "inside" the vertical edges of the aquarium before I add a new bead? <yes... completely> Q3 Does the inside bead add strength to the aquarium or is it for a seal? <just the latter> Thanks a bunch for the helpful advice I'm sure I will get! Tom USA High School Science Teacher <best of luck my friend. Anthony>

50 gallon aquarium reseal >I have a 50 gallon tank which I got for free and is old.  The tank is in near perfect condition still except that it has very small leaks along the edges where two sides of glass butt up against each other.  I tried resealing, with proper silicone, the edges which leak but it did not work and leaks in the same places. My question is what would be the proper way for me to seal my tank 100% good.  Can I just seal the inside corners, or do I have to take the panels apart and seal in between them also? Also, is it worth my time or should I buy a new one for $100.  Thank you Christian >>Hello Christian, you're talking to the woman who is all about cheap.  Ok, you didn't say what you did to prep the tank, so I'll give you the "blow by blow" on what to do.  You need to know that new silicone will NOT stick to old, this explains why you still have the leaks. >>First, you'll need to have on hand plenty of NEW straight edge razor blades.  100% silicone sealant (I really prefer what comes in the caulking tubes that you load up into the "gun" thingy), clean fresh water, isopropyl alcohol, and good light and ventilation. >>Using a straight edge, you will need to strip all (and I DO mean all) the silicone from the inside of the tank.  If you want to avoid releasing all panels, then be sure to make as clean and flat a cut into the corners as possible--you're going to be making a whole new seam on the inside. >>Then, after you've stripped away every bit of silicone, all the little bits that get hung up on the edges and so forth, you'll need to clean the glass so you can see if there is any residual silicone left--do this with the rubbing alcohol.  It will also remove any grease.  You can leave the tank out for a bit to let the alcohol evaporate, or you can rinse it, your choice.  If you haven't got the time for the second part, the tank can be left COVERED till you can get to the sealing part.  This must be done in one fell swoop...or one swell foop, whichever the case may be. >>Once you've determined that all inside edges are clean of silicone, dirt, debris, and grease, you can now setup to reseal. >>Be sure to have a pan/bowl of water right next to you, you'll be dipping your fingers into it to smooth the edge once you've drawn your bead.  Take the silicone, and you'll want the tip cut open to approximately 1/4", no more or you may end up with a mess (unless you're pulling too thin a bead--it needs to touch both pieces of glass).  You'll start on the corner of the floor of the tank, and draw your bead, being sure that you've got good, continuous contact on both pieces of glass AND well into the corner itself.  Even though the silicone won't seal to what's in there, you want NO air bubbles in any of these areas.  Air bubbles=weakness and leaks.  Draw the bead, then dip your finger into the water and, in one move, smooth the bead down, so it forms a wide "U" into the corner.  Do this for all for bottom edges, then move to the sides. >>Be sure to watch for air bubbles, if you get any then you'll need to wipe off the silicone and start again.  Practice makes perfect, so if you want to practice sealing up something else you can try it on cardboard, or even just consider the tank itself as practice. >>That should do it, if you've made a good seal on the inside then you ought to be able to avoid having to strip all the panels down.  Good luck, and let us know how it goes for you!  Marina

Re-sealing a fish tank Hi, <Hello> I just stumbled onto your website and you sound very experienced in the ways of the fish world.  I need some of your wisdom.  I have a 55 gallon fish tank that leaks at the bottom front.  I cleared out the old silicone from the front seam only and purchased some fish friendly silicone from my local pet store.  The tank is currently drying in front of a fan waiting for me to re-silicone it.  Here is my question:  Do I have to re-seal the WHOLE tank or can I just re-seal the one seam? <Best to re-seal all seams... cut out the existing seal, clean with a solvent, let dry, apply the new silicone, spread (with a tongue depressor, Popsicle stick, part of a clothespin...), let cure for a day or more, trim off the excess (with single-edge razor blades (be careful))... test outside over newspaper for leaks...>   Also, if I can re-seal the one seam how do I get the silicone to stick to the two corners it will become a part of? <Part of the problem with only trying one piece... you actually can't tell where the "leak" is originating... hence the call to do all seams> I've never done this before but I am quite anal when it comes to my fish, so I'm sure I'll do an excellent job. <Ah, good. Not hard to do, but easier the more times you do it. Do have plenty of paper towels on hand (to remove excess that gets on your hands. Good luck. Bob Fenner> Thank you for your wisdom. JavaMama

Glass and Silicone aquarium repairs. hey bob I have a oceanic hex 30 gallon take octagon shape tank. I have  leak on the side I started taking all the old sealant off but do u think if I reseal it will it be as strong as it once was????I have to take it all apart that's why I asking Julian <Would be as strong as it ever was/will be if indeed all the silicone were removed and re-done properly... Not easy to do however, and very time-consuming... How bad was the leak? It might well be that just resealing the "outside" bead would get you a water-tight tank. If this simpler repair doesn't work (test outside), I would look into getting a new tank. Bob Fenner>

Re: Glass aquarium repair try bob I am going to go ahead a try to reseal it. like u said it is time consuming. I took off all the old silicone but the pains of glass that make the octagon are glue together still holding the shape. can I just re-silicone the seams??? <Yes> also while cleaning the old silicone there is residue left over I want it clean as possible what can I use to remove the residue I cant get it with a razor and I've tried alcohol. and cleaner u recommend to completely remove any old silicone and residue. thanks for the help u give us. Julian <A solvent like Xylene or Acetone... and plenty of paper towels... and "elbow grease" (oh, and gloves for your hands if you think you might have a sensitivity... and do "outside" to alleviate fumes). Bob Fenner>

Silicone seals stained blue I have been treating my fish with Rid Ich and now the silicone seals in the corner of the tank have turned blue.  Is there anything I can use to take this staining out?  Any help would be appreciated.  Thank you. Laurie <Unfortunately there is nothing to remove the blue discoloring... you could cut out and re-silicone the tank... Not fun... next time, a separate treatment tank... or maybe you can make this one into your quarantine/treatment tank and just buy another... the tank w/o the top is often a bargain. Bob Fenner>

Chemical Residue 4/1/04 I have had a 29 gallon tank for almost a year and fell in love with keeping fish.  I just had to get a bigger one <We have all experienced this!> and recently made a great purchase on a 75 gallon tank with stand, hood and light.  The silicone was molded <<RMF would suggest to others to simply bleach wash here... covered on WWM> so I decided to remove it and redo the entire seal.  I was wanting to know if I was doing this correctly and when I did a search on this topic and found your site.  After reading on this topic I found that I was not far off base with the procedure I was using.  The acetone tip to take off the remainder of the old silicone was one I had never thought of.  My question is this:  With using the alcohol and then acetone for removal of the silicone, there will be a chemical residue left on the glass. <<Mmm, no residue left... all evaporates. RMF>> Would rinsing it off with plain water be sufficient or a combination of white vinegar and water, just plain white vinegar?  What would neutralize and/or remove the poisonous residue? "Superb information site and thanks"!  Cheryl <Just before re-sealing the tank, do a final wipe down with rubbing alcohol.  The alcohol evaporates completely and quickly leaving no residue. Avoid using water since it sometimes leaves water spots which will affect how well the silicone sticks.  Best Regards.  Adam>

Seam Failure Disaster Hi Bob and Crew, <Hello Jason> I hope you are all doing well. I on the other hand am not. I was the proud owner of a very happy setup up until recently. I had an Oceanic Systems 72 gallon Bowfront tank with a fairly sparse population of anemones - (three in total - my BTA split twice over two years) with a Clark's Clown, Yellow Tang blah blah - anyway to the point... I recently moved into a new place and was careful about handling my tank I made sure that it was drained completely and had no gravel or water in it before I moved it. After the move was finished and I had set up my tank ( at 5 am! finally) all was well again. My fish were really quite happy and everything seamed relatively unaffected by the move. I kept enough of the original water and sand all the live rock of course. I transported this stuff separately in individual buckets so that they would be fine when I set the tank back up. About a week later I got a call from my new landlord after I was called in from my vacation at around 4 pm. She regretfully informed me that my tank had flooded 2 of my neighbors apartments, plus mine. She then went on to tell me that she was unsure if any of my fish were still alive. I promptly left work and rushed home (ironically in the rain) I got home soaked to find all of my fish, inverts and anemones were placed in a bucket and my floor was mopped up for the most part but still was wet and salt residue remained all over my floors. The parquet flooring had mostly all warped, bubbled up and was popping off all over the place. This was not only in my apartment but in my neighbors as well. <What a nightmare!> At this point I pretty much felt like dying and my place was completely destroyed. I set up my hospital tank for the fish and anemones and disposed of the casualties ( 1 BTA, some Emerald Crabs ETC. ) I now have my entire setup in my bedroom -in two 35 Gallon PVC Buckets. I have sand, rock and fish in one tank. Just rock in the other - both are being circulated by two powerheads and have my lighting fixture overhead with airstones and a heater and all the rest of the kit. OK so here's the deal... I went to the place where I bought the tank and they gave me a new one. I reluctantly took the tank home and just put it on the Oceanic stand empty - I can't set it up until I get my new floors put in. I contacted someone at Oceanic Systems today and they said that they were not using the black sealant anymore as it was "defective" and they have switched over to a clear formula that they use on their 700 Gallon tanks. <... strange re the black sealant... it is used around the world, by some of the best manufacturers... and all the Oceanic Systems tanks I've seen have been well-built... and I don't recall a bow-front splitting a seam ever... but, who knows?> This doesn't help me much now cause the other tank I got has the black sealant on it - the one that they said was defective. So I suppose I would be okay with this if I got a new tank with the proper sealant but it still doesn't cover the fact that I am now responsible for paying out at least a couple thousand dollars in damages to my neighbors places. This does not cover the damages to my livestock / 90 lbs live rock etc... I had to take time off work to clean out some of the mess and do not have insurance as it was being processed when all this sh¡t happened. So this leaves me wondering where do I stand in the wake of this huge mess. This is enough to make me want to get out of the hobby for now anyways but I just bought about 1500 worth of new equipment - I had it mail ordered to Canada and have no money right now to pay for the damages etc.. I don't know - I just feel that I should have been notified that the sealant was defective I filled out my warranty form and everything - but getting a new tank is just the beginning - what about all the rest of the damages? <I don't know... but I would definitely pay some time, suffer some inconvenience to find out. Likely the first place to start is with your phone directory, one or two of the legal representation companies ("lawyers") in your area that do product liability, residential damage cases as yours... ask them how you might proceed. Next, I'd have them (for minimal money, no retainer) write a "demand letter" to the manufacturer asking for reimbursement of actual expenses...> Liability is a huge factor here. I guess I am talking to a lawyer tomorrow about it all but I wanted you to know some of the circumstances before I did. You have been a huge help to me in the past and I have written in on a number of occasions always getting nothing but the best advice possible in return. Is there anything that you can help me out with in terms of advice? <May be that I can be of further service. Our old companies had a few such liability instances (no fun!)...> I have another friend who is a Marine Biologist and services tanks in the area. he told me that he knows of six other people that have had the same problem with the exact same model of tank. I think others should be aware of this problem before they purchase an Oceanic Systems brand tank. <Mmm, did you fill in some sort of "warranty" registration and mail it to Oceanic? Am very surprised that they did not contact folks re this black silicone, failure problem if so> They have been great in dealing with the situation so far and were completely straight up about the defective sealant. I would like to deal with them in the future but I am reluctant as you could probably understand. Anyways - please help - what do I do??? Sincerely, JD <Talk with that attorney, and if you feel comfortable with enlisting their help, have them write that letter to Oceanic... and please keep me/us informed re the progress... and, please don't leave the hobby. Bob Fenner>

Re: Seam Failure Disaster Hi Bob, Crew <Jason> Thank you so very much for your response! - As always I appreciate your advice. I gave my livestock to an ex girlfriend who I got into the hobby and she has them all. They are alive and well in one of my old setups that I gave her. <Ah, good> As for the tank everyone seems to be very helpful thus far. I am still waiting to have the situation resolved but I am getting out of the hobby temporarily ( until I can get my setup up and running again ) I will keep you posted as to how this whole tragic turn of events pans out. Maybe I will put up a website? I wonder if "www.myfishtanksucks.com is taken" ? hah - I am just kidding but yeah anyways. <Actually... tank disasters I have known (as a book or .com) might be a very popular category. In the meanwhile, should you miss the interaction, you are (very) welcome to join us here helping other hobbyists by responding to queries> I might actually move from Toronto to San Francisco so this might have been Divine Intervention or something to that affect. <Both fine cities, for humans and pet-fishing> At this point I am taking it as a sign to pack up and go as it is something I have wanted to do for sometime. I am originally from California and don't really want to deal with another winter in Toronto.   - Thanks again. Cheers Jason <Be chatting, Bob Fenner> Repair question Hi, Just have a question: Is there a substitute I can use for aquarium sealant like from a hardware store? I know it is a Holiday weekend but I thought I would try! Thank you Michelle W <Yes, 100% Silicone is identical to "Aquarium" Sealant (it's also 100% Silicone)... just stay away from the "bathroom", "window" et al. non-100% Silicones that have mildewcides added. Bob Fenner>

Re: Repair question Thank you, I almost used the one that you said not to use, I will have to pick up one that is 100%, I was just going to use it for the outside of the aquarium but don't want to take the chance, and thank you for responding so quickly. Michelle W. <You are welcome my friend. Good luck with your project... take your time, use a tool like a tongue depressor or part of a clothes pin to smooth out the beads... allow to set up for a day, and trim off the excess (carefully) with single edged razor blades... easy to do/get a professional experience with patience. Bob Fenner>

All glass aquarium Hi John S. <MacL here with you tonight.> "Hi to all " I have a 150g ALL GLASS aq. Built in 1996, it is my understanding that it has tempered bottom glass. I would like to TRY to remove the bottom glass and replace with either a new piece of glass or acrylic that I can have drilled for corner overflows, do you have any suggestions? <I think you are going to find it very difficult to attach the acrylic to glass. Acrylic doesn't glue like glass does, it bonds or melts to another piece of acrylic or pvc with the right chemicals.> As far as removing the glass I was thinking of trying to push a thin piece of wire thru silicone, after cutting off most of it with a razor knife and then affixing a new piece of glass or acrylic with silicone? <To use new silicone you have got to remove all of the old silicone. Or you won't get a smooth attachment and might possibly have a leakage problem.  Also its very very difficult to drill glass. It tends to shatter. I'm thinking that you might want to consider contacting a glass place in your area for assistance in drilling.  Good luck John and if you still want to go forward with this I'll be glad to give you any assistance I can.> any help Thanks Sinc, John S.

Gluing the tank brace Mr. Bob Fenner About the tank brace that I must glue, could you tell me how much time needs the silicone to cure in this particular case. <I would give this a good two, three days... though the manufacturer states only 24 hours to cure.> I am thinking of: 1) emptying half tank as you recommended; 2) submerge three small powerheads in order to maintain good water motion because all the water movement by the sump, refugium and skimmers will stop during the curing time; 3) glue the brace, and wait 24 hours? <Better to wait two, three times as long> Could I try to gently remove some of the Valonia on the dried rocks ? <Yes, a good plan, time to do so. Bob Fenner> Thank you very much <Por nada my friend. Nos vemos> Flávio Ribeiro

Silicone sealant... Bob- Do you know of a specific brand of sealant in cartridges that is safe for use in a tank. I bought one at Home Depot that is made by GE and is 100% silicone. Since it did NOT say mildew resistant on the tube (where others do specify it) I thought it might be ok. Once I got home and put my glasses on to read the fine print on the back, it says not for use in aquariums. Thanks. Happy Holidays! Andy <Mmm, my long standing point on such matters... 100% is 100%... though the label may state something like "not for aquarium use"... have used the HD re-labeled products, RTV, other 100% silicones for aquariums for decades... One hundred percent... no mildewcides, other additives... Please take a stroll over the WetWebMedia.com site using the Search Tool and the word: silicone. Bob Fenner>

Used Gear Hello to all, <Howdy Gage> just a quick question. I read the section buying used gear, definitely the way to go when working with a budget. I am looking at a 100gal glass tank, 10years old, used only for freshwater, currently housing some cichlids. 10 years seems a little old to me, would you recommend resealing the tank before set up, or "if it ain't broke don't fix it"? remove as much of the old seal as possible then re-seal with aquarium silicone, or just seal over the old stuff? <Mmm, a tough one... I might well re-silicone the inside joints. If there's silicone there (as opposed to just between the glass piece joinings), gingerly (with single edged razor blades held at an angle... to prevent cutting into the joints) remove the old sealant, clean thoroughly with an organic solvent, rub dry with paper towels... and put in a good, new bead... maybe taper/flatten with a tool (tongue depressor, finger...), trimming away excess a day or more later...> Thanks. let me know if I am abusing your kindness by writing too often. I try to find the info on my own first, I read your site religiously. <You, we're doing just fine my friend. Bob Fenner> Thanks, Gage

Aquarium silicone (re-sealing a glass aquarium) I have a question... I am getting ready to reseal an aquarium, 65 gal. show tank. My plan is to cut the old silicon out with a razor, clean the area (maybe w/alcohol?) <Or other solvent, yes... a good idea. Wear rubber gloves> and apply new silicon. No one seems to do this type of repair or at least that I have found) they say if they do it would cost as much as buying a new tank. Okay I can agree with that, so am ready to do the project myself, but want to be prepared to do it right! <I've done this many times... not that hard... am not great with tools> My questions are... Is the clear silicon from a hardware store the same as something I could/would order online? <Just make sure it's "100% silicone"... other types have mildewcides (like for windows, tub and tile...) you want to avoid.> (by the time you pay shipping it triples *at least* the cost) What would be the best way to go about doing this? Best way to prep the glass? Anyone have experience in doing this? Please Help :-) Thanks, Monette <In a nutshell: Clean the tank, dry thoroughly, cut away old sealant (Single edge razor blade, watch your fingers!). , wipe off residue with clean rag and solvent, let dry completely. Run a continuous bead of new (100%) silicone in seams, wipe bead with tongue depressor, Popsicle stick, clothes pin, your finger... to smooth out... Let cure for at least a day... trim off excess (if so) with single edge razor blade... Put tank on level surface with newspaper under and fill up to test for leaks... Bob Fenner>

Re: aquarium silicon Thank you for replying so promptly!!! I was amazed you were so quick, and apologize that I have not sent a Thank You before now...3 kids /3 dogs and several (and growing in count all the time) aquariums keep me busy! <I just have the dogs... and have no time!> Again... a sincere Thank You!!! You answered all my questions plus! very helpful, Thanks to Susan aka Starsdawn I found your website! <Ahh, glad to make your acquaintance.> Have a Wonderful Day :-) Monette  

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