Building a 75g all glass tank

[fish590a]

Wendle,

Maybe I missed it, but do I apply the silicone on the front, back and bottom of sides?

[wendle]

Originally Posted by fish590a

Wendle,

Maybe I missed it, but do I apply the silicone on the front, back and bottom of sides?

Not sure if I am reading your question correctly, but if it is the question I think it is this is the best way to describe it;
You want a bead along the bottom of the inside face of the sides (calling them ends is maybe a little less confusing?)
You then want a bead along the bottom and both sides of the inside face of the front and back.
All beads should be applied to a "face" not an "edge".

I hope that makes sense, I am not much of a wordsmith.

Seeing as this thread seems to have remained a popular read, if I get time I would like to assemble a small tank and accompany it with a plethora of step-by-step photos.
I have a couple of tanks to build for people once I finish the car I am building, one of these tanks is a plain and simple 4' x 2' x 2'. That is probably a good candidate to photograph.

[scolley]

Originally Posted by wendle

Seeing as this thread seems to have remained a popular read, if I get time I would like to assemble a small tank and accompany it with a plethora of step-by-step photos.

That would be killer Wendle! If you get the chance, please do!

[Wasserpest]

Originally Posted by scolley

Assembly time
If you allow a silicone bead that goes between two pieces of glass to “skin over”, or form a slight film on its surface before you press the glass together, you should prepare for that seam to fail under pressure. Generally that means that you MUST press the glass in place within a few minutes of laying down the silicone bead. IMO 2 minutes is safe for the professional grade silicons I reccomended earlier, 5 minutes for commercial grades. Any longer and you are accepting an element of risk.

This sounds scary... so you have to really hurry (<2 minutes for RTV108) to get the silicone applied and the glass panes attached to each other.

[scolley]

That's why you need to practice on a little (cheap) tank first. And then practice EVERY SINGLE motion you are planning to make before you do it. And then, since you are only doing one pane at a time, that limit is not so bad.

[Wasserpest]

I hope 2 minutes is a bit on the extreme side. Working on a plywood tank, where the front glass needs to be glued on all 4 sides at the same time, I wonder if it is even possible to squeeze the cartridge fast enough to get it all out, and then lower the glass (slowly??) onto the glue.

Maybe for that purpose it would be better to use the non-professional type with less strength, but a bit more flexibility with the extended dry period.

[gmccreedy]

Wasserpest, speak with Jens. He did a bang up job on his 90 gallon (formerly Jay Luto's tank that ruptured). He may have some pointers for you!

[malaybiswas]

Hey Scolly

I have started my project on a 22 gallon ADA style rimless tank. While mine is not as ambitious as your 75 gallon project, I did read all 44 pages of that post. It was definitely informational and your perseverance is commendable.

I have a question on RTV108. I have been trying to find out that product and have searched at local HD, Lowes, Ace but not seen it. When I mention "RTV108", I get looks as if I just landed from Mars . Can you share a photo of it if you have so that I know what to look for next time?

Malay

[PDX-PLT]

Originally Posted by malaybiswas

I have a question on RTV108. I have been trying to find out that product and have searched at local HD, Lowes, Ace but not seen it. When I mention "RTV108", I get looks as if I just landed from Mars .

Google is your friend: http://www.altex.com/RTV-Silicone-Cl...8-P143191.aspx

[malaybiswas]

Originally Posted by PDX-PLT

Google is your friend: http://www.altex.com/RTV-Silicone-Cl...8-P143191.aspx

Thanks a lot PDX-PLT. They have this!!!

[_Green_]

Hi Scolley,

Thank you for posting this, I'm planning to build my own tank in the next month or so. I've worked with glass for some time now and really didn't think it would be very hard at all, actually I still don't, but your article did touch on a few things I hadn't thought of so thanks very much

The end result of your project looks out sanding. As I said above I'm planning my own tank and was told by more than a few people, (one of whom is the owner of the company I work for now) that I should not polish the panels because the seal will not be as good as it will in the glass is clean cut. So I'm wondering if you've had anymore problems with leaks since you last posted and how long has the tank had water in it?

Originally Posted by scolley

Well, I've gotten it from the experts that silicon sticks to silicon very, very well.

I've spent the last year installing 3-5 custom shower units 5 days a week and can tell you fresh silicone does not bond well to old silicone. Reapplying is a royal pain in the neck.

Originally Posted by scolley

I also got it from the experts that no silicon manufacturer makes silicon that they will say works for aquariums. Other companies buy the manufacturers' silicone, who then repackage it, and call it "aquarium" silicon.

That may be partially true, however CRLaurence Co. does manufacture a product specifically designed for aquarium uses see it here they do not sell to the public so that will make it more difficult to obtain. I also just noticed they state at the bottom of the product page that it's not to be used for frame less tanks over 30 gallons.

Originally Posted by scolley

As to the fresh stuff sticking... well I sprung a LOT of leaks before everything was OK, but I never sprung one at at point where I joined cured (or semi-cured) silicon to fresh. So I trust the advice of the experts on that - silicon sticks to silicon. Or at least it does if it is not old silicon.

Maybe your information is correct, I don't recall ever getting a call back to fix a leak where we had to remove and reinstall a panel. What I do recall is that the panels were a pain to get back into place because the old cone caused them to slide real easy on the shims.

[scolley]

Originally Posted by _Green_

I'm planning my own tank and was told by more than a few people, (one of whom is the owner of the company I work for now) that I should not polish the panels because the seal will not be as good as it will in the glass is clean cut.

That certainly sounds good. But keep in mind that the glass that the edge will abut to will be polished, so having one half of the bond getting a better grip may not help. Your likely point of failure is still silicone trying to remain adhered to polished glass. Maybe you minimize that risk because you've cut the number of such bonding surfaces in half. And do keep in mind, this is not about sealing - not in the sense that it's keeping the water in, and counteracting the pressure water is putting on the seal. That's not the dangerous stress. The danger is the pressure the water is putting on the wall of glass, creating shear forces that try to tear the edges apart. Resisting that requires strong adhesion strength, and silicone - as unlikely as this seems - is really poor at that.

Does that make sense? It's not the water pressure on the seal that's the problem. It's the water pressure on the huge pane of glass that creates the forces that tear the edges apart.

Originally Posted by _Green_

So I'm wondering if you've had anymore problems with leaks since you last posted and how long has the tank had water in it?

That tank had a massive failure one afternoon! Nearly 75 gallons on the floor within a minute or so. I've posted about that a lot here at PT. If you look, you'll find it.

By the time I learned about resonable construction techniques, and RTV108, I had developed a bit of bursitis in my arm from cleaning silicone. So while I knew that I SHOULD take apart the entire tank and use RTV108, I didn't. I only used it to repair leaking sides. As such, one long side was still attached with the old, crappy "aquarium" silicone. And about 12 hours after some hard pressure algae scrubbing on that side, it let go.

Originally Posted by _Green_

I've spent the last year installing 3-5 custom shower units 5 days a week and can tell you fresh silicone does not bond well to old silicone.

I believe I was referring to new, or freshly cured, silicone. If that was not clear, my apologies. My source was not referring to aged, dirty silicone.

Originally Posted by _Green_

however CRLaurence Co. does manufacture a product specifically designed for aquarium uses see it here they do not sell to the public so that will make it more difficult to obtain. I also just noticed they state at the bottom of the product page that it's not to be used for frame less tanks over 30 gallons.

Do they manufacture it? Or just market it? The intent of my statement is that no one "makes" aquarium silicone. Plenty of vendors buy "aquarium" possible silicone and market as such. And the one you found is only good for up to 30 gallons, which basically tells you that it is crap. I personally would not touch it. Get something that will hold.

Originally Posted by _Green_

Maybe your information is correct, I don't recall ever getting a call back to fix a leak where we had to remove and reinstall a panel.

Comparing the pressures on a shower door to an aquarium is comparing apples to oranges. Other than the fact that there is water in both situations, the applications, and the type of stresses that they put on silicone are very different.


Good luck with your project!

[sumoarigato]

Steve,

I can follow along why it's suggested that the four panes should sit outside the bottom pane rather than on top of it.

But...

Why are acrylic tanks made with the side panes sitting on top of the base pane? My initial thought would be to do exactly what you did. It just "seems logical" to put the four panes above the base to fully support the pressure.

Even given the difference of glass-meeting-silicon-meeting-glass vs. acrylic-chemically-bonding-to-acrylic, it still seems that water pressure would act the same way, requiring the same solution.

[gmccreedy]

Got me confused too. Although I believe the logic of the glass on the outside of the bottom base is because the silicone is stronger in tension then it is with a shear stress.

[Hoppy]

Just to complicate the discussion, GlassCages rimless tanks have extra strips of glass, same thickness, I think, "glued" to the inside of the bottom piece, on all four sides, so there is a double thickness of glass around the edges of that bottom piece. If Tom Barr is reading this thread he can confirm or correct this, because it is his tanks that I noticed this on. The effect of this would be to double the strength of the bond between the sides/front/back and the bottom piece.