Glass thickness for the big engineer minds

[nyvp]

my old tank was 120x36x30 1/2" sides and 3/4 bottom and was build like a tank. my new question is do you think that 3/4 glass is enough for a 96x60x48. Before your jump here is the reason I'm trying to stay at 3/4 instead of going to 1-1 1/2 is the use of starfire glass. of coarse price is a big reason as well.

Now here is my idea. think of a steel stand for the big tanks like this

http://i67.photobucket.com/albums/h310/nyvp/CIMG0343_edited.jpg


so the glass goes on the inside with a steel cage outside.

so instead of the usual silicon holding back the glass there will actually be a 2x2x1/4" worth of solid steel and the silicon is just a gasket.

Now if the glass is held back on all 4 side by 1" steel wouldn't it be stronger then just the 3 edges with just silicon? kind of instead of the water pulling at the silicon seal its effect is pushing on the glass.

with more firm seating and more points holding it back is 3/4 glass really going to crack?I was wondering if it would make a difference on the glass.

I'd like your engineering ideas. thanks ahead of time

[BeanAnimal]

A few thoughts without loooking at any numbers...

Aquarium glass thickness is determined based on the pressure and surface area of the glass, not the seam at the edges. While a larger cross section provides more adhesion, the limitation is the strength of the glass, not its bond at the edges. While adding structural support at the seams will certainly make the seams safer, it does not make the glass "stronger". A steel frame can eliminate the need for cross bracing. Part of the consideration is the bowing of the glass (the deflection). Of course, this will be greater along the longest edge, so adding a frome or cross bracing helps. However, that bracing is only a small part of the equation (at least for the nominal ratios of lengths and widths we use for aquarium).

So... (again I don't want to get into the math) the 3/4" glass built into a 96x60x48 tank will hold water with a safety factor of less than 1 (about .6 as a rough calculation). Adding a steel frame may increase that safety factor to a 1.5 or so... far below the comofort level of 2.5 - 3.5 that you should be shooting for.

[Neuticle]

If your steel frame is 100% flawless, then yes. But since this is not so possible in life, I think the stress density on the supports would be unacceptable for 3/4" glass.

[BeanAnimal]

Even if the steel frame was perfect... the safety factor on a panel that size under the pressure of 48" of water is still far less than acceptable :)

[Neuticle]

under the pressure of 48" of water is still far less than acceptable

Ouch, did not see the 48" deep specification. I agree.

[nyvp]

first let me say ty to the two of you for answering so quickly.

I've seen 3/4" used on sides 120x48x42" with 1" bottom on reg tanks and thats why I was hoping that with the added top brace, the safety factor would be covered to go up to the 48". I would think as a layman( and when it comes to math and engineering I'm close to the bottom of the list) that adding a brace where our usual tanks kinda try to stiffen up with out euro braces it would increase the factor more.

I know the width and height are the key factors in the stress equation even if the tank was 100 feet long. I have no problems with adding the extra cross braces/members. Is there someplace else beside going to 1 inch that would help?

btw going acrylic isnt an option for me and the panels in double 1/2 inch I think are really expensive.

[NanoReefWanabe]

btw going acrylic isnt an option for me and the panels in double 1/2 inch I think are really expensive.

one layman to the next...1200gallons of water on the floor is pretty expensive too...

i have seen you name around the boards for a long time now, and you know as well as everyone else the tank is generally the cheapest part of the build, and there is no sense under doing it, and there is no such thing as overdoing it...i am assuming the the tank is only cost prohibitive from the "it's only a tank" perspective, and not the actual financial one...and like you i have no glass engineering skills, but i would surely want her as thick as possible and then some...

the dimensions of this tank are almost identical to Oregon reef...wasn't that a glass tank too?

[nyvp]

NanoReefWanabe I hear ya. I also know we we sometimes go over the deep end to "bulletproof " our tanks and go a bit overboard . I will have to relook at 1" reg glass vs using 3/4 starfire and at 2 pcs of 1/2. Anyone know what double laminated panels cost?

[ycrazyy]

Laminated glass is not nearly as strong as regular glass, so I would not go that route if you can avoid it. 1" starfire glass is available in the US now a days through some suppliers, it is not impossible to find (if you need some contacts just PM me).

I am going to agree with the others here, under building, or building it on the cusp of widely accepted safety factors is probably not a good idea, especially on a tank this size.

[tkeracer619]

3/4 is in no way strong enough for a 48" tall 1200g tank.
They need to have a strong safety factor, without this you run the risk of some small incident causing complete failure.


I have a BS in Manufacturing Engineering and install/maintain tanks this size for a living. I would not install the tank you propose.

By the time you get the tank stocked the cost of the glass would be minimal.

[noobtothereef]

i think you would be better off using smaller panes of glass instead of it being all 1 piece , due to your exterior frame not being 100% perfectly flat, just cut glass panels to cover each opening in the frame, that way if the frame isnt perfect and the frame flexes it will have a little give and a larger margin for error

[noobtothereef]

something like this, the red is the vertical silicone joints and also the top and bottom will be held away from the frame with a bead of silicone, this design will alow you to use smaller sheets as larger the sheet is the more it is per sq. ft. You would also have to add more braces in the corners to give the glass something to lay against

scaled down a little bit
http://i178.photobucket.com/albums/w249/jimmyjames1981/18.jpg

[Acrylics]

btw going acrylic isnt an option for me and the panels in double 1/2 inch I think are really expensive.Given the span and height, IMO you'd need 1.5" thick panels for the verticals on this tank if you went acrylic, not doubled-up 1/2".

the dimensions of this tank are almost identical to Oregon reef...wasn't that a glass tank too?That tank was 1" acrylic and 90 x 72 x 30" high.

James

[chasekwe]

oregon reef was acrylic

[nyvp]

what would the safety factor increase by going up from 3/4 to 1" starfire? would that be enough?

[ycrazyy]

what would the safety factor increase by going up from 3/4 to 1" starfire? would that be enough?

You would have a smidgen over a 2.0 safety factor if you went with 25mm glass which IMO is still not enough to make me comfortable.

[nyvp]

what if i shortened the span to 56" like noobtothereef said above so it would be 56x60x48 . now are the model number tanking into account the 4 sided braces( top bottom,right and left ) that are different then a usual tank or it doesn't mater the numbers are the numbers?

[TheH]

Well are you going to tell us why you want it 48" deep? Purely aesthetic?

[nyvp]

my last tank was 120x36x30 560/g and I wanted to go bigger. After taking some measurements today and talking to the boss-lady I actually think I'd like try to go ........170x60x48 2000/g + depending on last measurements or if I have to come down to 45" height.
To answer your question why 48" my answer is why not? I love the way deep tanks look. My personal opinion is I don't like the long short squat tanks, but thats why this hobby works for everyone. I'm not worrying about lighting (solartubes) and I'm a big fish guy so going deep is fine. Ive seen a few 42-48" tanks and like the way they look much better. It will be the two long side viewable and I will have a way to actually get into the tank if I need to easily.
Hey if the wife will let me ( and I'm lucky to have her) who can say no. I just crunched some number and it looks like I can have it ready for water with plumbing,skimmer,lights,pumps,powerheads,structure work on house,stand and of coarse tank for 20k.

[NanoReefWanabe]

Hey if the wife will let me ( and I'm lucky to have her) who can say no. I just crunched some number and it looks like I can have it ready for water with plumbing,skimmer,lights,pumps,powerheads,structure work on house,stand and of coarse tank for 20k.

just be careful the peeps you buy all this from dont call the cops, cause at that price you are robbing them blind i would think...i am surprised you could get the tank for much less then that...mad props my friend....i will be watching like a crazed little fat kid seeing his first triple chocolate cheese cake smothered in fudge and caramel...

[noobtothereef]

170x60x48? If your house is a single story i would build that big of tank out of concrete and glass viewing panels , if not its going to have to be 2" or 3" thick material..... Which the tank itself's cost would be astranomical.........WAY over $20,000.

[nyvp]

noob and nao you are correct if it was a glass tank from a builder you are talking 15-20k maybe more just for the tank. I don't think iv'e seen a tank on RC yet built like this.

But have no fear I built and outfitted my old 560/g for much less, and it ran for a lot lower wattage then most people's 200/g's. It all came down to planning and doing a lot of the work myself. It took me a year but a lot of the items were used but in perfect condition. like for this tank i will have 8 tunze 6100's for flow that should run close to 175-200 a pcs.

To give you and idea on what wattage I will run this tank it should be close to 370/w powerheads/ if i can find the tunze 6300'sx4 used i can get that down by 100/w more, return is 165/w for Super dart skimmer, it's 65/w for a cone skimmer custom built like a ATB XXL but for a lot cheaper cost.solar tubes for bulk of light and 4 100/w five foot t5 for supplements and a ehiem 1262 80/w running my little items. thats a total of 600/w +/- before the T5's kick in to run a 2000/g tank. Thats still a 15-20x turnover.

The tank will be made out of steel,2 side glass 2 short side and bottom will be pvc. The tank itself and i'm working on the glass prices still will hopefully come in close to the $8000 range thats for the steel frame, two glass sides and two short sided and bottom out of PVC.

This will be a hybrid built tank that has a lot of the plywood DIY ideas but I didn't want to have to play with sanding and resin.

As for the idea of concrete , yes my house is 1 story, but concrete would need to be to pretty thick for what I'm looking for. Someone can chime in but I don't think I can come close to 2" thick walls in concrete.

I made the stand above is 2x2x3/16th for $900 and when I build again i should be able to bring some of the costs down lower. I got a quote last night for 4x4x1/4 for the base stand was only about $6 /ft.

Again this is just still my preliminary start for the build. I needed to figure the glass costs first and the engineering side down as well before I can get a def end cost and I'm sure there will be over runs....there always is.Good news is then comes the fun:fish1:. My goal is to have it built by end if year ....but we will see.:wave:

[noobtothereef]

Alot of people always say that when you diy tanks and equipment that you dont save much money considering theres labor involed but that quotes only true for lazy credit card type of people, i know that my setup that i am building would have no way of been feasible without diy'ing everything like you are doing, if you were the credit card type a tank like that with all of the equipment would be upward of $50,000+ , theres ALOT of tried and true plywood tanks that have been built on this site that look amazing, all it takes is imagination and some sheer enginuity to pull off a build with this magnitude for a somewhat feasible cost.

For the pvc bottom, sheets of pvc thick enough to handle the eight and stress would be very expensive, i ould at least do a plywood bottom and sides that come up about 6" for s spot for the glass to sit in, but then if i went that far i would use timbers for the side post(glass supports) and then frame the top, all wood construction with some really thick material. tHis is about the same method that bass pro shop used for theyre 3000+ gallon tank located in theyre restaraunt , i worked there and watched the whole build from start to finish when they were building the place, it has 3 panels of acrylic 2" thick and are about 10'x10' each with a 12" timber at each joint and is lagged bolted to the back of the timber and it looks amazing, the other 3 walls are framed with 2x12 engineered boards(laminated) and 2 layers of 3/4" sanded plywood on the insdie and epoxied to about 1/2" thick, they were dumping it in the tank with buckets in the bottom, didnt get to see them do the sides, the outside of the walls are sprayed with a foam insulation of some sort.

So the 4x4 tube is $6 a foot your going to have some cash into that frame, at least $1500 in material, for that much i can buy enough lumber to frame the whole first floor of a house, i would do the whole thing out of wood and cedar timbers running verticle between the panels of glass/acrylic and epoxy the **** out of it. Next i would adjust your dimensions so that you use full or half sheets (4x8) so you dont have drops and are getting what you pay for, if you order say a 80"x48" panel your going to pay for the whole 96" piece as the shop isnt going to eat a piece of drop that cost that much per sq.ft., but if you order 48"x48" pieces you wll use the whole sheet, or if they can get 120" long sheets for the same $ per sq.ft. figure them from that size sheet etc...

sorry im a avid diy'er and just giving you some ideas, im sure i will take some critisism as i always do with my ideas on here........

[nyvp]

For the pvc bottom, sheets of pvc thick enough to handle the eight and stress would be very expensive,

>>> you have to remember that the bottom and two short sides will have the 2x2 steel square every 2 ft so I wont need as thick of pvc that you think.

So the 4x4 tube is $6 a foot your going to have some cash into that frame, at least $1500 in material,

>> the 4x4's are just for the base stand which comes out to 60' in 20' sections x3 of 4x4 x $6 = $360
the tank cage will be out of 2x2 and 2x3 steel 1/4 inch steel

Im not set on the middle member I may use 2x3x1/4
but just for the 2x2 should be about 100' worth at $4 all in all less than 1k for the steel.

if i really want to get crazy i can get 180' of solid steel 2x2 yes solid for $1500 but it would weigh 2k by itself : )
I wonder what the bend factor would be for that stuff

something like this stand in middle but with 4 more added legs not just the straight bottom.


http://reefcentral.com/forums/showthread.php?t=1330053&page=5

[Neuticle]

My vote is for reinforced fiberglass with glass viewing pane.

[NanoReefWanabe]

i am pretty sure the bending strength of the hollow tube is better then that of the solid of equal size...

[sirpentor]

edit: linking to other forums is not permitted.

[sirpentor]

Fellas i have seen swimming pools maded with tempered 0.5 inch glass holding back serious gallons of water

it can be done
cheers

[nyvp]

Link removed.

where is the large section just saw nano

ty for the info

[BeanAnimal]

Hello nyvp

i am just reading your post.....please have a look at ultimatereef.com peek into their large tank sections , they have built monsters with just 3/4 panes of glass and steel frames


hope this helps........mark

Respectfully, you can't cheat physics. A "monster" tank can mean a lot of things with regard to actual panel dimensions and support. As mentioned earlier, the 3/4" panel used as proposed here would likely hold water. The problem is that there would be little to no safety factor. Chances of catastrophic failure would be many times that of a tank designed with a proper safety factor.

[BeanAnimal]

Fellas i have seen swimming pools maded with tempered 0.5 inch glass holding back serious gallons of water

it can be done
cheers

See the post above... you can't cheat physics. What was the surface area of the glass? What was the tensile strength? Was it tempered? Etc...

[Neuticle]

i am pretty sure the bending strength of the hollow tube is better then that of the solid of equal size...

Not how it works, if you're curious you can look up "second moment of inertia" and "radius of gyration".

[HarrsCars]

Just seen youre question and I dont have a answer. But there is a tank on the ultimate reef forum that is 13' by 6' by 3.5' and it is all 3/4 and built on site. Called John & Cams Bali Reef amazing stuff they did.

Just a thought
Mike

[nyvp]

i found the thread its under UltimateReef > Main Forums > Member's Tank Specs > Supersized tanks

Tank Dimensions are 12 x 6 x 3.5. 1885/g 1" bottom 3/4 sides using angle iron. No center brace or top brace like I was thinking. The frame is not even close to the str of what I was talking about doing(Well the base is beefy for sure).
Ty for the info it def renewed my idea's and belief that it can be done. Its been up for 1.5 years really nice tank.

[nyvp]

sorry correct it's 13 not 12 feet

[H20ENG]

We just put in an AGE tank- 60Lx30Wx48H- 3/4 starphire. I told them they were crazy, but AGE swore up and down that they do it all the time. He sent me megs and megs of pics of deep 3/4" glass tanks- never a failure.

Still sketches me out though...

I met Derek from Miracles awhile back and he said he would never make a tank that tall with 3/4.

FWIW...

Oh, and good to see you NYVP

[nyvp]

good to see you 2.
It;s been a while glad 2009 is over.
AGE make real nice tanks and are very reputable builder from what Iv'e heard.
I'll be back here again soon with a new build thread as soon as I have my basics down and I finish my last honey do for my wife.( I need to finish last project I started and didn't finish (bathroom)then it's off to the races.

[H20ENG]

as soon as I finish my last honey do for my wife.

Ha Ha, like there is EVER a "last" honey-do :hammer:

[nyvp]

Ok ..... Ok I get your point :spin2: your right till the day I die I will have Honey-do's.
My wife said finish your last project (bathroom) and then you can start another. She of coarse has no idea how big i'm going, but has a Slight idea of who I am from past projects & knows I only build things one way . :lol2:

[NanoReefWanabe]

Not how it works, if you're curious you can look up "second moment of inertia" and "radius of gyration".

and do you have a weblink or a comparative chart for those of use who are laymen?

[BeanAnimal]

It is a bit more complicated than just looking at a chart. If you look up rdius of gyration, buckling and moment of intertia, you will find enough physics to keep you busy for a while. If you want the "all-in-one" quick tour, visit the wikipedia pages for those aspects of physics :)

For a given diameter, solid beats hollow. However, weight for weight the hollow will outperform the solid.

[Neuticle]

For a given diameter, solid beats hollow. However, weight for weight the hollow will outperform the solid.

Yup, that's it in a nutshell.

The parallel axis states that the moment of inertia for a cross section is Ad^2. A=area and d= distance from the neutral axis. You can see that distance from the axis is very important, but a solid bar will have far more x-sectional area.

Radius of gyration is similar, but computes area further as a mass quantity. You could use the radius of gyration to compute how big of a pipe it would take to equal a bar of certain size.

[BeanAnimal]

I keep meaning to build physics 101 pages for my site, and show how certain aspects relate to our hobby. I got most of the thermo article done and half of the hydraulics and fluids article done and just need time to finish both. ... I also started a glass thickness one, but my physics are lacking a bit for what I want to do with it. :)