Calling all engineers and tank builders

[Nate Chalk]

I see a total volume of about 280 gallons. Shouldnt that be in your first set of calculations on the build sheet @UncommonSense ?
is the left side of the tank completely unsupported? If so the leverage effect of that cantilever will direct incredible forces on the corner joint of the drop-off.
The front and back panes of the upper tank will need to be thick enough to hold the forces of that cantilever and that left panel underneath the upper tank will need to be very thick since it is carrying essentially the weight of the whole tank plus the shear forces of the cantilever. I am not an engineer and dont know how to calculate the actual forces applied to these areas. I have years of practical structural experience and just pointing out some areas of concern. @BeanAnimal might have knowledge of the correct formulas or know who does.

It's fully supported I just didn't draw it in. Haha

 

[UncommonSense]

I see a total volume of about 280 gallons. Shouldnt that be in your first set of calculations on the build sheet @UncommonSense ?

It is, but I can only fit so much in one screenshot!

Also, ~280g is the volume the tank displaces (that is, outside dimensions)… after glass thickness, and not running the tank to the point of overflowing, it’s maybe a 240-250g tank!

 

[UncommonSense]

A unique issue with this design worries me. That is torsional force along the z axis (green). Silicon is weakest to torsional force and can tear so make sure you have enough support on the two points I circled to prevent any torsion. Or in other words, don’t do a Red Sea and have a floating front or back pane.

Excellent point!

A big “gotcha” with these drop-off tanks is also that short deep segment vertical pane; specifically the joint between it, and the shallow segment bottom pane!

— that particular silicone joint has to be dead on/perfectly perpendicular, or it ends up being the design’s weakest link! (I immediately think of reinforcing that seam… possibly inside, and outside, as added insurance!)

 

[Nate Chalk]

Excellent point!

A big “gotcha” with these drop-off tanks is also that short deep segment vertical pane; specifically the joint between it, and the shallow segment bottom pane!

— that particular silicone joint has to be dead on/perfectly perpendicular, or it ends up being the design’s weakest link! (I immediately think of reinforcing that seam… possibly inside, and outside, as added insurance!)

Reinforced I've thought about using a longer panel that goes up past the joint like the Fiji.

That stacked with inside euro

 

[UncommonSense]

Reinforced I've thought about using a longer panel that goes up past the joint like the Fiji.

That stacked with inside euro

That would definitely work! The oversized vertical deep pane acts to strengthen the “box” in that weakest area, and holds back shallow section sand!

I suppose you could also add vertical seam reinforcements (basically right triangle/right pentagon profile glass rods) in each of those corners to help reinforce those “weak” link seams…

(technically, all glass meets minimum spec… thicker reinforced seams just mean each one is under less stress per square inch, thus theoretically lasts longer!)

 

[Nate Chalk]

That would definitely work! The oversized vertical deep pane acts to strengthen the “box” in that weakest area, and holds back shallow section sand!

I suppose you could also add vertical seam reinforcements (basically right triangle/right pentagon profile glass rods) in each of those corners to help reinforce those “weak” link seams…

(technically, all glass meets minimum spec… thicker reinforced seams just mean each one is under less stress per square inch, thus theoretically lasts longer!)

They make triangle glass rods!? Smort.

I'll try to mock up pieces list then this week and get that sorted.

From there I can get quotes on glass.

Building it in the same room as the current tank makes it easy to lift it up and over right?

We barely got the current one down the hill and through.

 

[UncommonSense]

They make triangle glass rods!?

Technically, yes… I have seen a few rare instances of manufacturers or repairers using these! Though, they aren’t exactly something one could buy last time I checked… I ended up making my own!

From there I can get quotes on glass.

This one might provide a bit of sticker shock… raw glass prices are through the roof over the past year…

Building it in the same room as the current tank makes it easy to lift it up and over right?

Uh… you might want to build this one in situ on the stand! It’s going to weigh well north of 500 lbs all said and done!

We barely got the current one down the hill and through.

Yeah this one isn’t going to be very movable once built with this shape… more or less a move on the stand situation!

 

[Nate Chalk]

I've given some thought to panels and thicknesses

Exact millimeters

16mm- Annealed glass regular
Shallow end- 609.6mm x 762mm - 32mm to account for being inside (colored red)
Deep middle- 457.2mm x 762mm - 32mm to account for being inside (colored red)
Back panel- per spec sheet

16mm- Low iron glass annealed
Front viewing panel- per spec sheet
Deep end- 1016mm x 762mm - 32mm to account for being inside (colored red)

19mm- Annealed glass regular
Shallow bottom- 1066.8mm x 762mm

~31mm- Annealed glass regular
Deep bottom- 762mm x 762mm

12mm- Annealed glass regular
Euro bracing TBD

Planning for rimless top, but love the idea of triangle cut rods, will see if shop around the corner can do that for euro bracing. Would even put in every corner if it helps.

What material do people use for corner guards? is it just aluminum sheet corner molding? likely doesnt help seam strength much? but will cover up my ugly imperfections.

 

[UncommonSense]

Exact millimeters

16mm- Annealed glass regular
Shallow end- 609.6mm x 762mm - 32mm to account for being inside (colored red)
Deep middle- 457.2mm x 762mm - 32mm to account for being inside (colored red)
Back panel- per spec sheet

16mm- Low iron glass annealed
Front viewing panel- per spec sheet
Deep end- 1016mm x 762mm - 32mm to account for being inside (colored red)

19mm- Annealed glass regular
Shallow bottom- 1066.8mm x 762mm

~31mm- Annealed glass regular
Deep bottom- 762mm x 762mm

12mm- Annealed glass regular
Euro bracing TBD

Very nice! 12mm thick eurobrace should do it, though you could also ask if there will be any 3-4” wide strips of the 19mm sheet you could take advantage of for the 50% increase in seam thickness it offers!

Planning for rimless top, but love the idea of triangle cut rods, will see if shop around the corner can do that for euro bracing. Would even put in every corner if it helps.

What material do people use for corner guards? is it just aluminum sheet corner molding? likely doesnt help seam strength much? but will cover up my ugly imperfections.

The eurobrace is primarily there to act like a rigid spine, preventing the top of each vertical pane from bowing! — the thin glass rods won’t help much for this… however, they do work great in vertical seam inside corners!

— I went straight for glass to do my vertical seam reinforcements, a good bit of it is documented in my build thread, in fact!

— Aluminum would be an iffy choice, primarily because it corrodes when exposed to saltwater, so you’d need to fully encase it in silicone!

—Acrylic right triangle rods would work, and do exist, though these would be best served getting chemically treated/etched to improve silicone adhesion…

Red Sea uses a flimsy, floppy plastic strips as their seam “armor”, as I recently discovered!

(Yes, you can literally tie it in a knot…)

 

[Nate Chalk]

Very nice! 12mm thick eurobrace should do it, though you could also ask if there will be any 3-4” wide strips of the 19mm sheet you could take advantage of for the 50% increase in seam thickness it offers!


The eurobrace is primarily there to act like a rigid spine, preventing the top of each vertical pane from bowing! — the thin glass rods won’t help much for this… however, they do work great in vertical seam inside corners!

— I went straight for glass to do my vertical seam reinforcements, a good bit of it is documented in my build thread, in fact!

— Aluminum would be an iffy choice, primarily because it corrodes when exposed to saltwater, so you’d need to fully encase it in silicone!

—Acrylic right triangle rods would work, and do exist, though these would be best served getting chemically treated/etched to improve silicone adhesion…

Red Sea uses a flimsy, floppy plastic strips as their seam “armor”, as I recently discovered!

(Yes, you can literally tie it in a knot…)

Interesting, I wonder whats used then on the outside...further research there for options.

I currently have zero bowing with 1/2 inch glass across my 6ft section though the water heigh is 18 inches vs the 24 predicted here. I feel that the bowing wont be as pronounced with the drop off being introduced, but those seams should almost certainly be reinforced with the rods.

 

[Nate Chalk]

Is this how thick the glass is on the polo reef build??? or is it a seam cover.

 

[UncommonSense]

Is this how thick the glass is on the polo reef build??? or is it a seam cover.

That appears to be all glass, no filler there!

 

[Nate Chalk]

Any way to calc the bowing on a drop off


I really do wonder if this project will just work as is.

My last build is holding up great with my very poor seams with bubbles.

 

[UncommonSense]

Any way to calc the bowing on a drop off

For the specific L corner in the glass pane? That’s a tough one… most deflection calculators work off a square/rectangular pane shape!

I really do wonder if this project will just work as is.

My last build is holding up great with my very poor seams with bubbles.

Just keep in mind that you’re going from around 18” (~.66psi) to 40” (~1.48PSI) here, and the existing 1/2” glass is a bit over-spec at 18” tall, making up for some of the silicone voids!

 

[Nate Chalk]

For the specific L corner in the glass pane? That’s a tough one… most deflection calculators work off a square/rectangular pane shape!


Just keep in mind that you’re going from around 18” (~.66psi) to 40” (~1.48PSI) here, and the existing 1/2” glass is a bit over-spec at 18” tall, making up for some of the silicone voids!

Right, I would rather over build always.

Aligned with exactly all this. Trying to think if there's a way to be more sure about the specs we have created.

Before, not just the money but also the time and then fill date comes around. I avoid catastrophe.

 

[UncommonSense]

Right, I would rather over build always.

Aligned with exactly all this. Trying to think if there's a way to be more sure about the specs we have created.

Before, not just the money but also the time and then fill date comes around. I avoid catastrophe.

Hmm… I’m working off theory for a tank this size/shape…

best-bet would be asking a professional tank builder their opinions on the design choices before proceeding to ordering any materials!

 

[Nate Chalk]

Hmm… I’m working off theory for a tank this size/shape…

best-bet would be asking a professional tank builder their opinions on the design choices before proceeding to ordering any materials!

@Joe Glass Cages can someone on your team help a Cronie out?

This one cant be shipped or brought in the house. Has to be built in place. Happy to PM or give you a call.

I did dream of having ya'll build this on my behalf after visiting the shop and seeing the craftsmanship...

Posting again the picture of rough dimensions
*this will be fully supported with an 80/20 aluminum stand, it is not going to overhang.
Exact millimeters

16mm- Annealed glass regular
Shallow end- 609.6mm x 762mm - 32mm to account for being inside
Deep middle- 457.2mm x 762mm - 32mm to account for being inside
Back panel- per spec sheet

16mm- Low iron glass annealed
Front viewing panel- per spec sheet
Deep end- 1016mm x 762mm - 32mm to account for being inside

19mm- Annealed glass regular
Shallow bottom- 1066.8mm x 762mm

~31mm- Annealed glass regular
Deep bottom- 762mm x 762mm

12mm- Annealed glass regular
Euro bracing - wanting to go rimless, support the seams with glass rods. Euro brace the bottom but not the top.

 

[Nate Chalk]

@UncommonSense

If you have anyone else you think I should ping on thoughts please help :)

 

[UncommonSense]

Hmm… @oreo54 has gotten into some pretty intense structural calculations in the past…

— would you be willing to check our work, in addition to Joe?

 

[Nate Chalk]

Hmm… @oreo54 has gotten into some pretty intense structural calculations in the past…

— would you be willing to checking our work, in addition to Joe?

I should show the room and path otherwise, which is the reason for this feat.