New Free Tank, almost a good deal

[MCary]

Aquired a 225 gallon tank for 0 duckets. Unfortunately it has a leak in one corner. I was going to go against wisdom and remove 8 inches of the silicone bead from the x,y,z axis and rebead it. But I have removed silicone before and this stuff came off way too easy. So I've decided to do as I am told and remove the enite inside bead and re-caulk it with some new and improved silicone.

My question, Is the thickness of the silicone important? I mean within reason, not paper thin. I assume the width is important. Say 3/4-1inch on bottom and sides. But for instance if I use the old wet finger technique to smooth the bead, will there be enough silicone in the corner.

Mike

 

[hllywd]

I wonder if All Glass or another manufacturer might have ideas to help you... In my experience the seal between the panels is very important not just the bead.... 225 gallons would be a lot on the floor...

 

[windsor-aquatic]

Your suggestion of removing all the old silicone and replacing it should work out fine; it's the silicone beading that makes the tank water-tight. Be sure to clean the glass thoroughly with meths or similar before applying the new silicone. Once the seams are done, I would suggest applying a forther bit in each of the 4 corners, by way of reinforcement. If you want to get a straight finish on the seams, instead of your finger try using the rounded end of a socket extension; it takes a little practice to judge how much silicone to apply, but the finish, when done correctly, will look quite professional.

 

[BeanAnimal]

The bead ensure water tightness, but doesnt the thin film between the panes crete the strength?

 

[windsor-aquatic]

No, the strength is determined by the choice of glass thickness, bracing bars or a combination of both.

 

[hllywd]

<a href=showthread.php?s=&postid=6958070#post6958070 target=_blank>Originally posted</a> by windsor-aquatic
Your suggestion of removing all the old silicone and replacing it should work out fine; it's the silicone beading that makes the tank water-tight. Be sure to clean the glass thoroughly with meths or similar before applying the new silicone. Once the seams are done, I would suggest applying a forther bit in each of the 4 corners, by way of reinforcement. If you want to get a straight finish on the seams, instead of your finger try using the rounded end of a socket extension; it takes a little practice to judge how much silicone to apply, but the finish, when done correctly, will look quite professional.

Respectfully I will disagree. I've personally tried my hand at resealing a few tanks. doing the inside bead only, in my experience, produced unreliable results. I think I was pretty meticulous removing the old silicone and cleaning the glass prior to putting the new silicone on. The most reliable way was the PIA method of taking the tank apart and resetting the glass. One of the biggest problems is that silicone doesn't adhere very well to silicone so where the new stuff overlaps the old you endup with a weak spot. The largest tank I ever tried to reseal never got water in it after I fixed it since I dropped it getting it out of the truck....

I do like your tooling idea!

Like I said a 225 isn't a "throw away" tank. I'd like to here what a manufacturer has to say about repairs.

Tim

 

[rutledgek]

I built a sump and had a leak out of a side. Running a new bead downt he seam did seal it and I have no structural problems. Though a 20g sump is a far cry from a 225.

 

[MCary]

Thanks tons for the replies. Last night I removed the silicone from the inside. Completely taking down the tank and resealing is a last option. The silicone came off surprisingly easy which makes me glad I'm replacing it. I ordered some all-glass silicone. I've used 100% silicone before that said "safe for food use" and "not for aquarium use" and it worked fine but I went with the recommended stuff just for laughs.

Not sure I understand the socket extension thing. You run it down the seam with the extension basiclly oriented lengthwise with the round edge down? Do you wet it? What about a rubber spatula? I bought a can of acetone that I had planned on cleaning the glass with, is that okay?

Thanks again,

Mike

PS I planned on masking off the area with the bead to have nice straight edges and avoid slop on the glass. It this an unnecessary step using the ol socket ext. method?

 

[windsor-aquatic]

Re. socket extension: apply a line of silicone, wet the end of the socket extension (the rounded end) and run it up the seam, once only. Finish off the corners as mentioned earlier by hand.

 

[BeanAnimal]

<a href=showthread.php?s=&postid=6958378#post6958378 target=_blank>Originally posted</a> by windsor-aquatic
No, the strength is determined by the choice of glass thickness, bracing bars or a combination of both.

Not to be arguementative... but you lost me here.

I have seen a number of large glass tanks with NO perimeter bracing (thick enough glass to prevent failure due to deflection of the long panes). What does the glass thickness have to do with the bond between panes (unless of course the film of silicone is the strongest part of the joint!).

Are you saying that dry butt jounts with a bead if silicone are as strong as wet joined panes with a bead if silicone? It just ins't going to happen. I would contend (and have read someplace) that it is just the opposite. A properly joined corner will have a film of silicone between the panes, and will be almost as strong as the same joint with a "bead" or "fillet" of silicone applied. From my understanding the fillet is to add a bit of extra strength, but more to ensure a water tight and fairly protected joint.

Thoughts?

 

[MCary]

Not answering your question Bean, just an aside. The glass on this tank is 3/4" and it has a top center brace. The silicone butt joints are then say 6 feet long and 3/4 inch wide for the longest edge. The amount of pressure it would take to rip apart that joint must be huge. Plus the bracing and the internal bead would add to its strength.

I do know that the size of the glass has more to do with the contact area needed to hold than the strength of the glass. I'm sure 1/2 inch glass would easily hold 225 gallons without breaking, but the seams may give due to smaller contact surface. Or am I wrong?

Mike

 

[69vette]

The maximum bond strength with silicon rubber is acheived with a bond thickness of .004". The recommended bond thickness is .004"-.016". As the thickness rises, the bond strength diminishes.

Obviously the fillets don't fall into this category, but it would be interesting to build a tank with just the fillets and see what happens when it's filled with water.

 

[MCary]

Cool, I have an aquarium manufactuer and an engineer helping me. Where else can you get that sort of help for free, I ask you?

Thanks guys

 

[BeanAnimal]

69Vette... that is what I thought. I am not sure where I learned that, but it is something that stuck with me over the years.

 

[hllywd]

"not for aquarium use"

....usually means the silicone contains a fungicide or anti-microbial substance to preevent mildew and the like. Usually bad things when it comes to marine critters...

Remember too with what ever you do, just because you glop more sealant on doesn't mean the joint is stronger.

Good luck! Let us know what happens....

 

[bassnman11]

I tape off the seams with blue tape, apply the silicone and use the corner of a old credit card to smoothe. You can change the radius on the corner to suit your project. After it sets up, peel the tape for a pro looking job.

 

[hllywd]

Corona... I have an Aunt and Uncle there... Who you retired from bassnman?

 

[AggieBrandon]

I use the backside of a plastic spoon to smooth out my silicone...works pretty good

 

[hahnmeister]

FWIW, I have 'rebuilt' about 3 aquariums now. Each time I learned a bit more of course. Replacing the fillet on the inside is of little use IMO. The fillet itself is of little use on a well-built glass tank. I have seen glass tanks made without the fillet all together, and not only were the corners nicer looking, but the strength is just as good...like 69vette pointed out, its the silicone smooshed in between the panels of glass that gives the strength and will also give the seal in a well made aquarium.

If you want to do it right, remove the entire panel.

And for easy cleaning, use acetone. It eats up silicone fast and allows you to simply rub it off with a rag. It works great at cleaning up the glass and then off you go!

For the fillets, you have a few options. J. Turner, ORA and RAS founder, puts a super fat silicone 'rope' into every corner, and then comes back with a special razor...pretty much a straight razor bent in two places to make the silicone into a triangle/ flat diagonal bead. I use a piece of PVC...larger pipe like 3/4 or 1" for larger tanks, and 1/2" for smaller. I run the edge of the pipe along the bead after I squeeze it into the corner. Later on, there will be a 'rope' of silicone along the outside edges of the fillet that simply gets razor bladed out. The other option would be to simply practice with a caulk gun on enough pieces that by the time you have to use it, you can lay a neat bead in one motion of the caulk gun without any retouch. This takes some talent...but if you practive on scrap for a bit...youll see what I mean.

 

[MCary]

100% silcone that is "safe for food use" does not have any antifungicides and is adentical to aquarium silicone. I am convinced that the "not for aquarium use" statement is a liability issure. They don't want to get sued if the seam fails.