resealing a glass tank ?

cmacld · 09/13/2009, 09:05 PM

im in need of some help.. i just purchased a new 150 gallon glass tank.. however one of the sides of the tank has begun to split... so i need to reseal one end of the tank for sure, but i have never had to work with a tank that has totally started splitting.. how should i go about this.. i imagine that i need to remove the end piece of glass and reseal the whole side? any help would be greatly appriciated!

Cheers

Everyones Hero · 09/13/2009, 09:12 PM

I have a 55g that I need to reseal so I'm in.

cmacld · 09/14/2009, 02:11 AM

nobody has any info?

billdogg · 09/14/2009, 07:09 AM

if you bought it new why not just take it back??? should be a warranty fix

coralnut99 · 09/14/2009, 10:12 AM

Quote:

Originally posted by billdogg
if you bought it new why not just take it back??? should be a warranty fix

There's lots of info available, but I couldn't agree more. You'd be in for a TON of work on something that's brand new. I wouldn't let too much time go by, some warranties are ridiculously short.

coralnut99 · 09/14/2009, 10:18 AM

Quote:

Originally posted by billdogg
if you bought it new why not just take it back??? should be a warranty fix

There's lots of info available, but I couldn't agree more. You'd be in for a TON of work on something that's brand new. I wouldn't let too much time go by, some warranties are ridiculously short.

cmacld · 09/14/2009, 10:43 AM

this would be NEW to ME... not new from the store

coralnut99 · 09/14/2009, 11:02 AM

Quote:

Originally posted by cmacld
this would be NEW to ME... not new from the store

That makes things a bit clearer.

Is the top brace still intact? Just curious how you determined that he seam is failing?

cmacld · 09/14/2009, 11:50 AM

the top brace is still intact.. however it is cracked a bit in places and i will be replacing it. You can phyically pull the side panel away from the back panel. seal is broke about 6" starting at the top of the tank. ill try to post a few pics later.

Sorry about the mix up earlier guys... i should have made that clearer

coralnut99 · 09/14/2009, 12:20 PM

Quote:

Originally posted by cmacld
the top brace is still intact.. however it is cracked a bit in places and i will be replacing it. You can phyically pull the side panel away from the back panel. seal is broke about 6" starting at the top of the tank. ill try to post a few pics later.

Sorry about the mix up earlier guys... i should have made that clearer

I think you've summed it up pretty good. I think most here will advise tearing it down completely, and re-doing the inner and outer silicone beads.

I guess I'll be the first one to tell you that this will be a significant investment of time on your part. I can't possinly tell you exactly how much time, but I can promise you won't get it done in a weekend.

Tearing it down is just takes a lot of patience. Removing the top brace is actually the hardest part. A dremel tool with a cutoff wheel will help a lot. But this part actually carries the greatest possibility of chipping or cracking a pane if you're not really careful. The next toughest part is separating the panes, but since one seam is already compromised, you have a big leg up on it. Find the thinnest gauge wire you can find and tie a length of it off to a wooden dowel rod at each end and force it between the panes without "sawing" back and forth on the way down. Fishing line may work also.

The old silicone must be COMPLETELY removed. The only way is with a very sharp straight razor blade. You'll go though the better part of a box of them. Lightly buffing the area with a 400 grit sandpaper wil reveal any silicone you missed.

That should get you through the tear-down phase.

In cases where there's no firsthand experience working with silicone and glass, I always suggest just trying to build a small glass box first. It won't cost a fortune, and you can use the cheaper GE Silicone I just to get a feel for whether you even want to wade into this any deeper. You may actually want to give this a try before tearing it down. hth

coralnut99 · 09/14/2009, 12:25 PM

I'll just throw out one last comment on the "old vs. new" issue. Even if you bought it used, you bought a broken tank that won't hold water. I know I wouldn't be a happy camper if I didn't know it had a compromised seam when I paid for it.

Cuby2k · 09/14/2009, 09:38 PM

Quote:

Originally posted by coralnut99
. . .

Find the thinnest gauge wire you can find and tie a length of it off to a wooden dowel rod at each end and force it between the panes without "sawing" back and forth on the way down. Fishing line may work also.

The old silicone must be COMPLETELY removed.

Good advice.

I remember helping my dad remove windshields from cars (to replace them) when I was just a sprout. The piano wire trick was standard wisdom of the day that still applies. Also making sure that all the old stuff is cleaned off.

All that aside I have to say that if the prep work is complete, including cleaning with rubbing alcohol, silicone is pretty forgiving stuff.

Please keep us posted.

jmkarcz · 09/14/2009, 10:42 PM

In lieu of the piano wire, I have recently used a long piece of braided "Fire line" fishing line - about 10lb test. I used some "bias" along the flat panel side and not the end of the panel of glass as I "flossed" the silicone joint. This kept it from cutting the line.

Don't even attempt to do this on your own if your not planning on being "anal retentive" about removing every trace of silicone and then stripping the oils from your hands and other contaminants from the glass before resealing.... or it will surely leak.

Also... buy the correct silicone. I don't want to read about you needing advice on how to fix it when your silicone turns florescent green after a week.

Good luck... and from my last rim remove, cut panel, clean, replace and replace rim, start to finish... I would use a number of 6-8 hours for a beginner... done right... for someone on his 5th.. I can get it done in 4... but only the end panel- the front takes much longer.

Check into a new upper rim before you start from your local dealer. my buddy bought a new one for about 15$... it looks like new when done... and it made removal so much simpler not having to save the old one. (Sure you have to clean the upper rim - but you won't have to clean the groove in the old rim.) Cuts down some work.

khanb31 · 09/14/2009, 11:53 PM

Well,

Im just gonna post a PM that I told someone about a 175 gallon tank that I tore apart, cut the panes, and then put it back together. He wanted to do kinda the same thing you were going to do. He only had a small leak though. As far as im concerned, Youll need to do the full aquarium over again. You cant just put one pane back onto the old one (even after the info below). I wouldnt trust a parting line between the old and new silicone seams.

----------------------------------------------------

"Well, your plan has some things in it that I would not recommend.

First, Please please please do not cut out more silicone than you need. You should be able to trace any leak that is a problem with the tank. Realistically, the tank is held together with silicone. The bracing does not support the tank as much as everyone would suggest. Sure it "helps", but it only really contributes to keeping the VERY easily breakable glass edges safe. As far as us engineers are concerned, it does nothing but make the tank more idiot proof. After building my new tank, I found out how brittle and how strong glass is. AND, ANY defect in the glass pane can result in a total failure. Period, end of story. Get new glass!

Second, do NOT just scrape off the old silicone and pour some acetone over the glass and then re-seam it! I dont care HOW many times you went over it with the sharpest razor blade on the planet! (This next paragraph is the most amazing discovery that I made while doing tests for glass preparation and silicone adhesion.)

I had some of my panes cut, which meant that I had new edges of glass to work with. Totally silicone free in every way. Now, I also had on that same pane, edges that were adjacent that DID have old silicone scraped off. Here is the kicker. I took my finger and ran it across the new edge maybe 5 or 6 times. After that, I took that SAME finger and ran it along the old siliconed edge 5 or 6 times. You know what I felt? A VERY noticeable difference. The old siliconed edge was slippery. I also had 5 other people do the exact same procedure and every person confirmed the same results. What can you take from that? The old siliconed edges still have silicone stuck in the very pores of the glass.

One engineer at glass cages told me that theres a reason why no one makes their tanks out of old glass: the seams DONT hold. Why? because the new silicone just CANT adhere to silcone filled glass.

This is why my edge preparations and adhesion tests were SO important. I concluded that if you cant get new glass, make your old seams like new! So, I ground down enough of the edge were ALL the silicone was in order to get rid of the top layer of silicone filled glass. I used an 80 grit sand paper on an orbital sander to really rough up the glass. It should be a completely Frosted look after you done and unable to look through it.

You cannot and I repeat CANNOT, Just put everything back together again after youve pulled it apart. You have to do the necessary steps that will allow you to silicone BRAND NEW GLASS. This is the only way to do it successfully and the right way. If you dont your seams will fail!

Do you have any questions? Do I make sense? "

-------------------------------------

It took me 2.5 months and counting to make my system. 1 month of that was research (with professional engineers), edge preparations, adhesion tests, and meticulous scraping and cleaning.

Your in for a world of hurt....

If you want me to give you even more info on how I went about doing it. Please send me a pm.....I will have no problem talking with you about it in the most realistic way possible.

JTL · 09/15/2009, 06:54 AM

I respectfully disagree that you cannot re-silicone glass. I recently built a tank and had to take it apart, clean it up and re-silicone it again, only to do it a third time. The re-siliconed glass had bonded to the point where I was concerned I may not be able to get it apart. I am convinced that that key to constructing or reconstructing a tank is to use a very good adhesive grade silicone like RTV 108 or 103 (black) and make sure the glass is squeaky clean.

I used 6 lb test fishing line and razor blades from a disposable razor (they are paper thin) to get the seams apart. Regular razor blades, acetone and very fine steel wool to clean off the old silly.

Uncleof6 knows more about this than just about anyone, but I am learning, the hard way.

coralnut99 · 09/15/2009, 07:16 AM

fwiw, I respectfully disagree with the re-siliconing thing too. Half of my fishroom is composed of canabalized tanks that came back to life as custom refugiums, and frag tanks. For me, sticking with fresh razor blades, and roughing up the surface to reveal any silicone I missed has seemed to work just fine.

Everyones Hero · 09/15/2009, 10:32 AM

If you're not supposed to re-silicone tanks why is it recommended that they be re-siliconed every 15 years or so?

I'm sure it's time consuming to do it right, but it's not rocket science by any stretch of the imagination.

SNAKEMANVET · 09/15/2009, 12:23 PM

I had to replace the bottom glass if a 240,that had been dropped and broke.I bought a new piece for the bottom,I used a drill with a wire brush to remove old silicone.After replacing the glass it has been holding fine for 1 year.Just make sure all the old silicone and residue is gone,you should be fine.

cmacld · 09/15/2009, 12:41 PM

lots of great info here! Thanks guys!!

nauticac4 · 09/15/2009, 02:44 PM

I just did this with a 3ft cube and 2 months later is still holding water.

1.Remove the panel and clean it, then clean it again and when your done with that clean it one more time to be sure.

2.Use RTV 103 or 108 (one is clear one is black) you can get it from Grainger for about 10 bucks a tube. Get a few just in case.

3.Lay masking tape on the glass allowing for the glass and the "seam" of silicone.

4.Get a helper and glue everything together with a nice healthy bead of silicone. To much is better than not enough, you can clean it up later.

5.Put some weight on the glass to press out the excess silicone and fill any air bubbles ( You only want about 1/16" of silicone between the panels)

6.Run your finger up the inside to round the excess silicone and remove the masking tape.

7.Let it cure until the smell is gone.

JTL · 09/15/2009, 03:23 PM

I will be doing it tomorrow.

Cuby2k · 09/15/2009, 08:18 PM

Quote:

Originally posted by khanb31
Well,

. .. . .
One engineer at glass cages told me that theres a reason why no one makes their tanks out of old glass: the seams DONT hold. Why? because the new silicone just CANT adhere to silcone filled glass.

. . . .

Wow, that's some interesting stuff. Seems logical.

khanb31 · 09/15/2009, 10:48 PM

Everyones Hero: Ive actually never heard of that before. Do you remember where you heard that from? Its very interesting.... Has anyone else ever heard of an "overhaul" of a tank after so many years?

nauticac4 "7.Let it cure until the smell is gone."

I personally would be very cautious with this. One of the surface adhesion tests that I did on some spare glass actually didnt cure thoroughly in two days. I am using half inch glass and when I ripped apart the seam after two days, it was still uncured silicone inside. I was using RTV 732 though (I got it from glass cages). Both have a full cure time of 7 days. I would be VERY cautious about cure times.

I got my info from these websites.
http://www.mgchemicals.com/products/108.html
http://www2.dowcorning.com/DataFiles...c8801e3848.pdf

If I were to do this again, I would use the RTV 108. It has a tensile strength of 400 PSI vs. the 333 PSI for the RTV 732.

Coralnut99 & JTL Thankyou for keeping this a civil conversation. I love that. Respect is something few and far between these days.

I definitely agree with the types of silicones you guys are using. You must use the right type which really affects how strong you seams come out.

I know that for the people that have succeeded in re-siliconing tanks, it has "worked." But, I must admit one thing about the approach behind my findings: I try to have a more "ideal" (for lack of a better word) scenario in which my odds are with me and not against me. This definitely comes from my background with engineering and only facilitates my point.

Even though a reseaming of a tank seems to work for some people, i dont believe that this could have been the best scenario that could have been set up to solve the problem.

Now, I will admit, I used the wrong words in my previous post. Cannot is not the right word for this type of discussion. I would replace all of those "cannots" with "I wouldnt recommend."

I think actually that its more of a discussion about how strong these seams are for how long. I am personally coming from the mentality of, (as if i was talking to myself) "hmm....now if I wanted to build a tank....how would i do it?" Well, most things are obvious. When you get down to the important parts though, which would you rather have?

1- a seam where you know its hugging and clinging off of old siliconed glass?

2- a seam where you know its hugging and clinging off of new glass?

If i was a tank manufacturer, I would choose the 2nd option because it rules out one unknown. And thus from that, I chose to put in the time to make all of my edges "new glass."

I hope I am making sense?

Also, After I pulled apart my old tank, my findings about the difference in the surface friction between the old and new siliconed edges fortified my decisions about what actions to take.

I know that if my fiance found out that my custom built tank (120 gallons) busted a seam in our new apartment. Im sure id loose my left leg and our land lord (her dad), would kill me! Thats yet another reason why I needed to make sure that this tank lasted FOREVER. I put HUGE beads on this tank (compared to any professionaly made tank like AGA).

And at the end of this entire thing, theres only one thing that is really important. It is applicable to many things....

understand the consequences of your decisions

I imagine everyone else would agree with that one...

Thanks

Jim

JTL · 09/16/2009, 06:28 AM

We will likely never agree on the subject of re-siliconing glass but I can tell you this. From my experience you can in fact get the glass clean enough to re apply silicone and create a lasting bond. I just cleaned some glass it was so clean it literally "squeaked", not something it would do if there was any residue remaining. I also performed your new glass vs used glass test and found absolutely no difference in the "feel". I really think it is all in the cleaning technique. I have found that using steel wool and acetone after scraping with razor blades is the most efficient method.

Even with new glass it is very important to thoroughly clean the mating surfaces with acetone just before assembly to insure a good bond. It doesn't take long for a film to develop on glass, especially if has been handled.

Cure times vary with temp, RH and thickness of the silicone. It takes up to 7 days to fully cure but can be handled sooner. An aquarium seam does not need to be very thick, only about one mm. Thicker seams may even do more harm than good, plus they don't look very nice IMO. The key is surface area, which is why some manufacturers use euro bracing around the bottom in lieu of a thicker bottom panel. The same is true for the inside bead. I like the look of a thin (2mm) bead that you can make by taping off the joint. This is a must if you are using black silicone. The bead only protects the seam and gives some additional protection against leakage.

Having read just about every post on DIY tanks I personally think people are taking a greater risk by not properly sizing the glass for their tanks than they are by re-siliconing. Generally speaking anything over 90-100 gallons requires 3/4" glass. Height being the most important consideration. The glass calculators available online are for tanks with exterior bracing, not rimless. Additional considerations are required to build a structurally sound rimless tank, like thicker glass and/or euro bracing. Having said that I built mine using 1/2" side panels and a 3/4" bottom panel. At 90 gallons I am borderline.

That is the extent of my knowledge on the subject.
John

khanb31 · 09/16/2009, 08:29 PM

John (JTL)-

Actually, I noticed something about your last post that peaked my interest.

Quote:

Originally posted by JTL
....

I have found that using steel wool and acetone after scraping with razor blades is the most efficient method.

...

That steel wool might in fact be doing exactly what I did with sand paper on my edges. Not to the extreme that I did of course, but It might just have been enough? Something to think about i suppose.

As far as the "feel" of the glass that i mentioned earlier, I cant imagine any clean glass not squeaking? The really interesting part about the difference in the edges was when there was water applied to each edge.

Now, I must clarify, I only scraped off the old silicone and no preparations were done to the edge after that. Im not sure if you had done the finger feeling test before or after you cleaned it with steel/acetone. I did mine prior to any edge preparations. I then did the finger feel test and also a syringe dropping single drops of water along each edge (across its length).

Before I siliconed anything together, I wanted to firmly confirm that there was silicone imbedded in the top layer of the glass even though our eyes told us it looks no difference from virgin glass. The reason I used the water can be explained by surface energy from fluid mechanics. A common use of this is called a sessile drop technique which can be used to evaluate the surface tension of a fluid -or- the surface friction coefficient of a material. The links below can explain it very well if your interested in it.

http://en.wikipedia.org/wiki/Surface_energy
http://en.wikipedia.org/wiki/Sessile_drop_technique

Its really fun stuff and this technique really gave me a visual representation of the difference in the surface friction coefficients. What I found is that on the old siliconed glass, the water droplet was more of a half spherical shape while the new glass had a more flattened shape (like the picture illustrated on the surface energy wiki page). When I have some time Ill see if I can recreate the same results and take some macro shots of them. I could probably even find out the difference in the friction coefficients if the findings are easy enough to decipher.

I guess I should have said that in the first place and im sorry for omitting that. Ill try not to be so lazy next time.

In regards to glass thickness, I agree with you on your findings. Height and width of a tank really dictate the thickness of the glass. With my tank being just around 115 gallons with outside dimensions being 68"L x 30"W x 15.5"T, 1/2" vertical panels were a must. 3/4" for the bottom pane was also required because of the width.

Im actually very glad this conversation came up because regardless of whether or not we agree or if either of us is correct, we are posting our findings and ideas onto the website. This will give everyone else another reason behind whatever decision that they make.

09/13/2009, 09:05 PM	#1
cmacld Registered Member Join Date: Jun 2005 Location: Colorado Posts: 608	resealing a glass tank ? im in need of some help.. i just purchased a new 150 gallon glass tank.. however one of the sides of the tank has begun to split... so i need to reseal one end of the tank for sure, but i have never had to work with a tank that has totally started splitting.. how should i go about this.. i imagine that i need to remove the end piece of glass and reseal the whole side? any help would be greatly appriciated! Cheers __________________ The Schnazzberries taste like Schnazzberries........ Current Tank Info: 100g rimless

09/14/2009, 02:11 AM	#3
cmacld Registered Member Join Date: Jun 2005 Location: Colorado Posts: 608	nobody has any info? __________________ The Schnazzberries taste like Schnazzberries........ Current Tank Info: 100g rimless

09/14/2009, 07:09 AM	#4
billdogg Registered Member Join Date: Apr 2008 Location: Grove City, Ohio Posts: 10,806	if you bought it new why not just take it back??? should be a warranty fix __________________ I'll try to be nice if you try to be smarter! I can't help that I grow older, but you can't make me grow up! Current Tank Info: 120 mixed reef with 40b sump, RO 150 skimmer, AI Sol Blue x 2, and a 60g Frag Tank with 100g rubbermaid sump. 2 x Kessil A360w lights, BM curve 5 skimmer

09/14/2009, 10:43 AM	#7
cmacld Registered Member Join Date: Jun 2005 Location: Colorado Posts: 608	this would be NEW to ME... not new from the store __________________ The Schnazzberries taste like Schnazzberries........ Current Tank Info: 100g rimless

09/14/2009, 11:50 AM	#9
cmacld Registered Member Join Date: Jun 2005 Location: Colorado Posts: 608	the top brace is still intact.. however it is cracked a bit in places and i will be replacing it. You can phyically pull the side panel away from the back panel. seal is broke about 6" starting at the top of the tank. ill try to post a few pics later. Sorry about the mix up earlier guys... i should have made that clearer __________________ The Schnazzberries taste like Schnazzberries........ Current Tank Info: 100g rimless

09/13/2009, 09:12 PM	#2
Everyones Hero Registered Member. Join Date: Jun 2008 Location: Leonardtown, MD Posts: 1,154	I have a 55g that I need to reseal so I'm in.

09/14/2009, 12:25 PM	#11
coralnut99 Registered Member Join Date: Oct 2003 Location: Bushkill, PA Posts: 3,632	I'll just throw out one last comment on the "old vs. new" issue. Even if you bought it used, you bought a broken tank that won't hold water. I know I wouldn't be a happy camper if I didn't know it had a compromised seam when I paid for it. __________________ Why can't my wife see this stuff as an investment? Current Tank Info: way too much to list, and still adding more!

09/14/2009, 10:42 PM	#13
jmkarcz Registered Member Join Date: Feb 2003 Posts: 2,728	In lieu of the piano wire, I have recently used a long piece of braided "Fire line" fishing line - about 10lb test. I used some "bias" along the flat panel side and not the end of the panel of glass as I "flossed" the silicone joint. This kept it from cutting the line. Don't even attempt to do this on your own if your not planning on being "anal retentive" about removing every trace of silicone and then stripping the oils from your hands and other contaminants from the glass before resealing.... or it will surely leak. Also... buy the correct silicone. I don't want to read about you needing advice on how to fix it when your silicone turns florescent green after a week. Good luck... and from my last rim remove, cut panel, clean, replace and replace rim, start to finish... I would use a number of 6-8 hours for a beginner... done right... for someone on his 5th.. I can get it done in 4... but only the end panel- the front takes much longer. Check into a new upper rim before you start from your local dealer. my buddy bought a new one for about 15$... it looks like new when done... and it made removal so much simpler not having to save the old one. (Sure you have to clean the upper rim - but you won't have to clean the groove in the old rim.) Cuts down some work.

09/14/2009, 11:53 PM	#14
khanb31 SLim Jim Join Date: Apr 2008 Location: Near Ohare, Des Plaines 60016 Posts: 1,096	Well, Im just gonna post a PM that I told someone about a 175 gallon tank that I tore apart, cut the panes, and then put it back together. He wanted to do kinda the same thing you were going to do. He only had a small leak though. As far as im concerned, Youll need to do the full aquarium over again. You cant just put one pane back onto the old one (even after the info below). I wouldnt trust a parting line between the old and new silicone seams. ---------------------------------------------------- "Well, your plan has some things in it that I would not recommend. First, Please please please do not cut out more silicone than you need. You should be able to trace any leak that is a problem with the tank. Realistically, the tank is held together with silicone. The bracing does not support the tank as much as everyone would suggest. Sure it "helps", but it only really contributes to keeping the VERY easily breakable glass edges safe. As far as us engineers are concerned, it does nothing but make the tank more idiot proof. After building my new tank, I found out how brittle and how strong glass is. AND, ANY defect in the glass pane can result in a total failure. Period, end of story. Get new glass! Second, do NOT just scrape off the old silicone and pour some acetone over the glass and then re-seam it! I dont care HOW many times you went over it with the sharpest razor blade on the planet! (This next paragraph is the most amazing discovery that I made while doing tests for glass preparation and silicone adhesion.) I had some of my panes cut, which meant that I had new edges of glass to work with. Totally silicone free in every way. Now, I also had on that same pane, edges that were adjacent that DID have old silicone scraped off. Here is the kicker. I took my finger and ran it across the new edge maybe 5 or 6 times. After that, I took that SAME finger and ran it along the old siliconed edge 5 or 6 times. You know what I felt? A VERY noticeable difference. The old siliconed edge was slippery. I also had 5 other people do the exact same procedure and every person confirmed the same results. What can you take from that? The old siliconed edges still have silicone stuck in the very pores of the glass. One engineer at glass cages told me that theres a reason why no one makes their tanks out of old glass: the seams DONT hold. Why? because the new silicone just CANT adhere to silcone filled glass. This is why my edge preparations and adhesion tests were SO important. I concluded that if you cant get new glass, make your old seams like new! So, I ground down enough of the edge were ALL the silicone was in order to get rid of the top layer of silicone filled glass. I used an 80 grit sand paper on an orbital sander to really rough up the glass. It should be a completely Frosted look after you done and unable to look through it. You cannot and I repeat CANNOT, Just put everything back together again after youve pulled it apart. You have to do the necessary steps that will allow you to silicone BRAND NEW GLASS. This is the only way to do it successfully and the right way. If you dont your seams will fail! Do you have any questions? Do I make sense? " ------------------------------------- It took me 2.5 months and counting to make my system. 1 month of that was research (with professional engineers), edge preparations, adhesion tests, and meticulous scraping and cleaning. Your in for a world of hurt.... If you want me to give you even more info on how I went about doing it. Please send me a pm.....I will have no problem talking with you about it in the most realistic way possible.

09/15/2009, 06:54 AM	#15
JTL Registered Member Join Date: Jun 2003 Location: Venice Island, FL Posts: 2,532	I respectfully disagree that you cannot re-silicone glass. I recently built a tank and had to take it apart, clean it up and re-silicone it again, only to do it a third time. The re-siliconed glass had bonded to the point where I was concerned I may not be able to get it apart. I am convinced that that key to constructing or reconstructing a tank is to use a very good adhesive grade silicone like RTV 108 or 103 (black) and make sure the glass is squeaky clean. I used 6 lb test fishing line and razor blades from a disposable razor (they are paper thin) to get the seams apart. Regular razor blades, acetone and very fine steel wool to clean off the old silly. Uncleof6 knows more about this than just about anyone, but I am learning, the hard way. __________________ John 100 gallon DT and 50 gallon sump with refugium. Reefbreeders Photon V2+.

09/15/2009, 07:16 AM	#16
coralnut99 Registered Member Join Date: Oct 2003 Location: Bushkill, PA Posts: 3,632	fwiw, I respectfully disagree with the re-siliconing thing too. Half of my fishroom is composed of canabalized tanks that came back to life as custom refugiums, and frag tanks. For me, sticking with fresh razor blades, and roughing up the surface to reveal any silicone I missed has seemed to work just fine. __________________ Why can't my wife see this stuff as an investment? Current Tank Info: way too much to list, and still adding more!

09/15/2009, 10:32 AM	#17
Everyones Hero Registered Member. Join Date: Jun 2008 Location: Leonardtown, MD Posts: 1,154	If you're not supposed to re-silicone tanks why is it recommended that they be re-siliconed every 15 years or so? I'm sure it's time consuming to do it right, but it's not rocket science by any stretch of the imagination.

09/15/2009, 12:23 PM	#18
SNAKEMANVET PREMIUM MEMBER Join Date: Jul 2005 Location: TRENTON Tn Posts: 4,486	I had to replace the bottom glass if a 240,that had been dropped and broke.I bought a new piece for the bottom,I used a drill with a wire brush to remove old silicone.After replacing the glass it has been holding fine for 1 year.Just make sure all the old silicone and residue is gone,you should be fine.

09/15/2009, 12:41 PM	#19
cmacld Registered Member Join Date: Jun 2005 Location: Colorado Posts: 608	lots of great info here! Thanks guys!! __________________ The Schnazzberries taste like Schnazzberries........ Current Tank Info: 100g rimless

09/15/2009, 02:44 PM	#20
nauticac4 Baby Fish Wrangler Join Date: Apr 2007 Location: Greenville, NC Posts: 1,237	I just did this with a 3ft cube and 2 months later is still holding water. 1.Remove the panel and clean it, then clean it again and when your done with that clean it one more time to be sure. 2.Use RTV 103 or 108 (one is clear one is black) you can get it from Grainger for about 10 bucks a tube. Get a few just in case. 3.Lay masking tape on the glass allowing for the glass and the "seam" of silicone. 4.Get a helper and glue everything together with a nice healthy bead of silicone. To much is better than not enough, you can clean it up later. 5.Put some weight on the glass to press out the excess silicone and fill any air bubbles ( You only want about 1/16" of silicone between the panels) 6.Run your finger up the inside to round the excess silicone and remove the masking tape. 7.Let it cure until the smell is gone. __________________ Put Wings on it and Let it Fly!!! PBITAWA !!! Current Tank Info: 180 Cube 3x3x3. 29Gallon Sump 20 Gallon Fuge (1) Lumenarc Reflector w. 250W ARO Ballast and - Modded GS1 Skimmer - Eheim 1262 Return - Vortech MP40W and Swirler Stein

09/15/2009, 03:23 PM	#21
JTL Registered Member Join Date: Jun 2003 Location: Venice Island, FL Posts: 2,532	I will be doing it tomorrow. __________________ John 100 gallon DT and 50 gallon sump with refugium. Reefbreeders Photon V2+.

09/15/2009, 10:48 PM	#23
khanb31 SLim Jim Join Date: Apr 2008 Location: Near Ohare, Des Plaines 60016 Posts: 1,096	Everyones Hero: Ive actually never heard of that before. Do you remember where you heard that from? Its very interesting.... Has anyone else ever heard of an "overhaul" of a tank after so many years? nauticac4 "7.Let it cure until the smell is gone." I personally would be very cautious with this. One of the surface adhesion tests that I did on some spare glass actually didnt cure thoroughly in two days. I am using half inch glass and when I ripped apart the seam after two days, it was still uncured silicone inside. I was using RTV 732 though (I got it from glass cages). Both have a full cure time of 7 days. I would be VERY cautious about cure times. I got my info from these websites. http://www.mgchemicals.com/products/108.html http://www2.dowcorning.com/DataFiles...c8801e3848.pdf If I were to do this again, I would use the RTV 108. It has a tensile strength of 400 PSI vs. the 333 PSI for the RTV 732. Coralnut99 & JTL Thankyou for keeping this a civil conversation. I love that. Respect is something few and far between these days. I definitely agree with the types of silicones you guys are using. You must use the right type which really affects how strong you seams come out. I know that for the people that have succeeded in re-siliconing tanks, it has "worked." But, I must admit one thing about the approach behind my findings: I try to have a more "ideal" (for lack of a better word) scenario in which my odds are with me and not against me. This definitely comes from my background with engineering and only facilitates my point. Even though a reseaming of a tank seems to work for some people, i dont believe that this could have been the best scenario that could have been set up to solve the problem. Now, I will admit, I used the wrong words in my previous post. Cannot is not the right word for this type of discussion. I would replace all of those "cannots" with "I wouldnt recommend." I think actually that its more of a discussion about how strong these seams are for how long. I am personally coming from the mentality of, (as if i was talking to myself) "hmm....now if I wanted to build a tank....how would i do it?" Well, most things are obvious. When you get down to the important parts though, which would you rather have? 1- a seam where you know its hugging and clinging off of old siliconed glass? 2- a seam where you know its hugging and clinging off of new glass? If i was a tank manufacturer, I would choose the 2nd option because it rules out one unknown. And thus from that, I chose to put in the time to make all of my edges "new glass." I hope I am making sense? Also, After I pulled apart my old tank, my findings about the difference in the surface friction between the old and new siliconed edges fortified my decisions about what actions to take. I know that if my fiance found out that my custom built tank (120 gallons) busted a seam in our new apartment. Im sure id loose my left leg and our land lord (her dad), would kill me! Thats yet another reason why I needed to make sure that this tank lasted FOREVER. I put HUGE beads on this tank (compared to any professionaly made tank like AGA). And at the end of this entire thing, theres only one thing that is really important. It is applicable to many things.... understand the consequences of your decisions I imagine everyone else would agree with that one... Thanks Jim

09/16/2009, 06:28 AM	#24
JTL Registered Member Join Date: Jun 2003 Location: Venice Island, FL Posts: 2,532	We will likely never agree on the subject of re-siliconing glass but I can tell you this. From my experience you can in fact get the glass clean enough to re apply silicone and create a lasting bond. I just cleaned some glass it was so clean it literally "squeaked", not something it would do if there was any residue remaining. I also performed your new glass vs used glass test and found absolutely no difference in the "feel". I really think it is all in the cleaning technique. I have found that using steel wool and acetone after scraping with razor blades is the most efficient method. Even with new glass it is very important to thoroughly clean the mating surfaces with acetone just before assembly to insure a good bond. It doesn't take long for a film to develop on glass, especially if has been handled. Cure times vary with temp, RH and thickness of the silicone. It takes up to 7 days to fully cure but can be handled sooner. An aquarium seam does not need to be very thick, only about one mm. Thicker seams may even do more harm than good, plus they don't look very nice IMO. The key is surface area, which is why some manufacturers use euro bracing around the bottom in lieu of a thicker bottom panel. The same is true for the inside bead. I like the look of a thin (2mm) bead that you can make by taping off the joint. This is a must if you are using black silicone. The bead only protects the seam and gives some additional protection against leakage. Having read just about every post on DIY tanks I personally think people are taking a greater risk by not properly sizing the glass for their tanks than they are by re-siliconing. Generally speaking anything over 90-100 gallons requires 3/4" glass. Height being the most important consideration. The glass calculators available online are for tanks with exterior bracing, not rimless. Additional considerations are required to build a structurally sound rimless tank, like thicker glass and/or euro bracing. Having said that I built mine using 1/2" side panels and a 3/4" bottom panel. At 90 gallons I am borderline. That is the extent of my knowledge on the subject. John __________________ John 100 gallon DT and 50 gallon sump with refugium. Reefbreeders Photon V2+.