Building a 75g all glass tank

[scolley]

Originally Posted by sumoarigato

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.

Glen had it right about the shear strength of silicone being poor, requiring sides against the bottom, rather than on it. I screwed up, and that seems clear in retrospect. But I know why I decided to do it the way I did, and I'd wager dollars to doughnuts that it's the same reason acrylic builders do it...

When you set the glass around the outside of the bottom, the measurements of the side panes becomes much more critical than if you set them on the bottom. Think about it. When you are placing side on top of the bottom, you pin four sides together, and as long as they come close to meeting the edges of the bottom pane, you're OK. But when you wrap them around the bottom, if they aren't perfectly cut, you could have some nasty gaps, or the interior of the sides could be larger than the bottom. Bad problem.

Placing sides around the bottom is far less forgiving of small mistakes in cutting. But with acrylic, you just make sure the bottom is bigger than the connected sides... bond them on to the bottom, and trim any bottom edge excess with an acrylic cutting router bit. Much easier. And the whole shear vs. adhesion thing doesn't matter at all with acrylic, because once bonded, acrylic seams are actually stronger than the acrylic sheets.

BTW - did I mention that I'm doing work in acrylic now? Never without a project.

[sumoarigato]

Steve (and Hoppy and Glenn),

Thanks... it all makes sense when you combine the nature of the bonds along with the feasability of cutting/trimming materials. With glass, you need those cuts to be consistent and even from the get-go, but with acrylic, post-trimming isn't a problem (and pretty much required anyways).

I also saw many comments about tracking down aquarium-safe silicone, and (before I read this thread) I simply wasn't able to locate any GE I in black (unless I wanted a case), nor any of the other tested alternatives easily. After a week of searching, I found a site that carries the All-Glass Aquarium Sealant (so we know it's as safe as we're gonna get), and it's only $6.50/10.3oz tube (!):

Clear:
http://www.herpsupplies.com/product....93&id=AAG65003

Black:
http://www.herpsupplies.com/product....92&id=AAG65004


Thanks again for this great post! I suspect you've saved many carpets/wood-floors with this thread!


I look forward to your acrylic experiment(s) as well!

[rountreesj]

Nowplan on doing a full rimless 36"x18"x18" tank with 1/2" glass. I need to get the final quote from a glass shop and an aquarium builder and see which is cheaper me doing it or someone else doing it. I feel confident that I can do it...But I just need to find where Steve says what kind of glass to use and why. Don't tell me, just point me where if you can, he told me to check the thread, but I think I missed it.

[bpkenn]

Wendle & Scolley,

Was hoping you guys could comment on my situation. I recently acquired a 45g hex tank with a leaking seam, and I am hoping to reseal it.

It looks as if there are gaps between all the pieces of glass, and there is plastic molding on the top and bottom. I assume that i could use the plastic molding to hold the glass pieces in places while i silicone them, but how can i do this effectively within 2 minutes?

Thanks in advance