Large rimless/braceless acrylic tank?

[arc eye]

I want to do a large rimless/brace less tank. The dimensions I am looking at doing are somewhere between 42"-48" in length, 30" in depth, and 18"-20" tall.

My goal is to peninsula the tank and have it look slightly off cube after accounting for a large coast to coast overflow in the back.

I was thinking of going with acrylic mainly for strength and clarity. I plan on having the tank made before I move to California in a year or so. My thoughts were that a large paned acrylic tank would stand a better chance of survival than a thinner paned starfire tank in the event of a sizable earthquake.

However, I spoke with a local acrylic tank builder and they weren't sure if a 1" acrylic tank of these dimensions could safely be done without at least some sort of corner braces.

If I were to go acrylic does anyone know how thick I would need to go?

I also thought acrylic would be cheaper, but after talking with TAP Plastics it looks like 1" acrylic sheets are going for around $32.85 per square foot. At that price glass almost seems cheaper...................although I haven't really investigated this yet.

Anyone else looked into something similar?

Any thoughts more than welcome.

Thanks in advance!

 

[arc eye]

anyone..........................bump

 

[Krish]

I think you'll run a risk doing a tank that size without a brace or bracing of some sort. There are a few sponsors here that build tanks so I'd talk to them and see if it is do-able. Just a thought...Good luck with the project!

 

[Notturnia]

make it with glass..
it wont require brace or other to bake safe

donno the price in US of glass tanks.. but here we do tanks up to 100" x 100" x 40" with 19mm glass w/o bracing..

just need someone that is really good using Silicon and will use the right glass and the right silicon..

but we usually do.. as i'll do on my 100" x 30" x 28" tank.. i may add some more glass on the top border to avoid fish to jump out and salt to rise over the border.. but not much more..

 

[roscoe]

I beleive ELOS will make you one. There is a member here that had one custom made by them, but it probally will cost you a few shinny pennys though Heres the link to his thread. http://www.reeffrontiers.com/forums/showthread.php?t=28885&highlight=elos

 

[big t]

I would definately go w/ glass for rimless tanks. Acrylic is just too flexible and will end up bowing over time. I am not sure that even 1.5" would not end up bowing. It would be perfectly safe, just look bad. Don't buy your plastic from TAP, let you tank builder buy it from their supplier, they will be able to get it much cheaper.

 

[arc eye]

bowing is definitely a concern of mine. Also the price if I were to go 1 inch or thicker gets pretty insane. Maybe I will look into glass. Are there any good west coast manufacturers that wouldn't be elos priced?.............could make for a good road trip though I suppose?

 

[Notturnia]

if i was in USA i would gladly come to silicons it for you..

btw.. from timoshenko calcs your glass should be a 12mm float glass to be w/o rim/brac

i would suggest to use 15mm to be safer and have a glass ring on the bottom to have 30mm of silicon fixing the lower part of the tank..

as i did on mine..

http://www.notturnia.com/foto/acquari/500/incollaggi/index.html

here is before i made the glass ring on the bottom..

after i build it and tested for the water i empty it and put other 12mm (i used 12mm) x 5cm glass on the bottom.. all around.. so i have twice the silicon on the bottom that keep the glass .. as there is the main pressure and i wont to have a swimming pool in the bedroom :doubt:

that tank was a 160 x 45 x 45 (cm) tank.. just to put at the end of my bad..

the new will be bigger but will use the same sys

 

[dnjan]

btw.. from timoshenko calcs your glass should be a 12mm float glass to be w/o rim/brac

What edge conditions do you use for your calcs? Free to rotate on all four edges but free to translate (move horizontally) only on the top?

What kind of point load did you include for cleaning purposes?

 

[Notturnia]

http://it.saint-gobain-glass.com/upload/files/3_2_calcolo_degli_spessori_pag_396-405.pdf

in italian sry..

using a common float glass with 6 MPa (N/mm2)

an arrow of 1/200 and 3 side blocked and 1 free to move (the upper) page 404 for the formula.


then usually i get one thickness more then the result to be safe..

in my tank i'm planing to use tempered.. or 2 layer tempered to life safer... also if a bit more expencive..

 

[Notturnia]

btw.. i dont calc a load for cleaning as usually i wont use the upper side to put my weight ..

 

[dnjan]

http://it.saint-gobain-glass.com/upload/files/3_2_calcolo_degli_spessori_pag_396-405.pdf

an arrow of 1/200 and 3 side blocked and 1 free to move (the upper) page 404 for the formula.

The one side free to move I follow, but what specifically do you mean by 3 side blocked. I think the english translation is 3-sides fixed, which means the ends cannot rotate (moment) or translate (shear stress). Correct?

Also, I am not sure what an arrow of 1/200 means.

Sorry for not understanding, but I have never worked with translations from Italian (just translations from German).

I'm not sure it is safe to ignore cleaning forces. In my experience, the loads applied while trying to scrape off corraline algae can be significant.

 

[arc eye]

Thank you for the input. However, I am more interested in having someone build it than trying to do it myself. I'm interested in making my own tank someday, but not one this large right off the bat!


so.......any west coast manufacturers?

 

[Notturnia]

The one side free to move I follow, but what specifically do you mean by 3 side blocked. I think the english translation is 3-sides fixed, which means the ends cannot rotate (moment) or translate (shear stress). Correct?

Also, I am not sure what an arrow of 1/200 means.

Sorry for not understanding, but I have never worked with translations from Italian (just translations from German).

I'm not sure it is safe to ignore cleaning forces. In my experience, the loads applied while trying to scrape off corraline algae can be significant.

yup fixed my english suck .. sry..
arrow of 1/200 means that hm.. if you have a tank 20 inch tall in the upper central part of the front glass when full of water the glass will move out for no more then 1/200 of the tall.. so 1/200 * 20 inch = 0,1 inch
so you wont have a perfect straigh glass cause the force of the water..

i dont use in the formula the cleaning force cause i usually over-calc the thickness of the glass i need to accept some hit while leaving near the tank..

so it's more strong then required..

then also think about in italy isnt easy to find a tank higher then 60 cm (23-25 inch) so usually you wont need to put weight on the glass..

same for float vs tempered.. float is safer IF will start to break cause it's slower to break.. tempered is harder to break.. but when it start it's matter of less then 1/100 of a second before you have your tank all around the house.. so for bigger tank i use dual layer tempered glasses.. so i have it stronger and safer (tnx to the plastic film inside) and then i have more possiblity to carry weight on it when cleaning the glasses..

btw.. if you need to clean the glass from algae you can use EASY-BLADE http://www.reefline.it/prodotti.php?category=14 that will prevent you to put hands in water and also stress the glasses..

hope this time i was more "understand-able"

 

[dnjan]

yup fixed my english suck .. sry..
arrow of 1/200 means that hm.. if you have a tank 20 inch tall in the upper central part of the front glass when full of water the glass will move out for no more then 1/200 of the tall.. so 1/200 * 20 inch = 0,1 inch
so you wont have a perfect straigh glass cause the force of the water..

Thanks for the clarification. You are limiting the deflection to 1/200 of the span (length). That makes sense. In this case, which was the critical design limit? Deflection (1/200) or stress?

I am not sure that having the ends fixed is a good assumption. You probably get some flexing at the corner (between the front and the side), which would make the stress and deflection in the middle higher than you calculated.

I agree that you probably have it covered by going to about 3mm thicker glass.

 

[Notturnia]

well the critical limit i use is the span.. i dont like to see a glass like an egg.. i know it will hold the water.. but i dont feel ok.. so usually i reduce the span from 1/200 to 1/400 using a thicker glass.. +3mm as you saw.. it will reduce a bit the stress and also the span and wont cost too much..

there is some flexing at the corner as i will use 2-3mm of silicon between the glasses and it can expand from 3mm to 3.1-3.2mm when with water.. but it's a "plus" not a trouble as it will let the glass to "move" under the heavy load of water and "tank" an hit safer as it's not hard-fixed like acrylic..

glass should let "move" a bit while acrylic do not need it..

ends fixed are "good" only if tempered dual/triple layer glasses so if they break the ends will keep the glass in position while you can work on the tank to save all before remove the glass.. but it's really expencive to create hard-fixed link for a glass..

so.. silicon "fixes" the ends.. permitting them to have a small small movement but not much to think about change the calcs.. also cause i use a double layer of glass for the botton.. 1 full glass + a brace/rim around (inside the tank) to have much more silicon.. so you reach something like a fixed bottom.. and the 2 other ends have only 1 thich of silicon due to 1 glass only..

for now it's working around europe ;-)