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Unread 02/24/2020, 09:43 PM   #1
Jade5051
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Glass bottom safety factor

Can someone please help me or point me in the right direction? I'm trying to calculate the thickness for a 3.8 safety factor on the bottom of a 28x28x17 aquarium. I'm using 0.5" glass for the sides and need to cut a 28x28 bottom but I don't know how thick the bottom needs to be. I've been looking on the interweb for over an hour now.


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Unread 02/24/2020, 09:52 PM   #2
Jade5051
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Finally found a calculator that says 8.5mm which would be 3/8" glass. I'd like to not have 55 gallons of water on the floor could anyone please reply? Does that sound right? I was going to do rimless if that makes a difference.


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Unread 02/25/2020, 08:46 AM   #3
mcgyvr
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@Jade5051
The answer depends on how the bottom is supported..


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Unread 02/26/2020, 08:40 AM   #4
lapin
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When in doubt and not being a seasoned builder I would error on the side of thicker.

Disclaimer:
Most of my glass tank experience is with the old metaframe slate bottom tanks.


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Tank sizes, 2-10's a 55 and one that's about 500gal

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Unread 02/27/2020, 12:43 PM   #5
oreo57
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Quote:
Originally Posted by Jade5051 View Post
Finally found a calculator that says 8.5mm which would be 3/8" glass. I'd like to not have 55 gallons of water on the floor could anyone please reply? Does that sound right? I was going to do rimless if that makes a difference.
3/8 = .375 = 9.5mm approx.
Should be thick enough..

Calc I play w/ given your dimensions (17 is DEPTH right) would give 3/8" bottom a safety factor of 4.8...


side glass needs to be only 6.4mm...283" thick.

If you actually go 1/2 sides just do 1/2 bottom..
Or all 3/8" glass.

l and width can't be equal thus the discrepancy ..and also rounded a bit.




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Unread 02/27/2020, 02:25 PM   #6
mcgyvr
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You want more than a 3.8 safety factor on a rimless tank..
Often they use near double (7-7.6) or more for rimless..


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Unread 02/27/2020, 03:40 PM   #7
oreo57
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Quote:
Originally Posted by mcgyvr View Post
You want more than a 3.8 safety factor on a rimless tank..
Often they use near double (7-7.6) or more for rimless..

AFAICT those calcs assume "free standing" i.e rimless..
1/2 thick glass bottom on a 50gal tank..for a factor of 7+ btw.

Quote:
The calculator calculates the bending of a glass pane with the forces that would be exerted by water on the pane if it was freestanding (supported on 4 corners, but not fixed).
https://www.marineaquariumsa.com/thr...ss-tank.48280/


Calc maker..and good discussion..


I have no problems w/ "overbuilding" anything..and would rarely settle for "minimum" thickness but don't see 3.6 as minimum..

You could check w/ Glasscages to see their glass thickness. They have a close tank size:

Quote:
40 Square (Rimless) 24 x 24 x 16 tall




Last edited by oreo57; 02/27/2020 at 03:48 PM.
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Unread 03/04/2020, 11:47 PM   #8
Jade5051
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The reason I'm using 1/2" glass for the sides is because it's scrap glass from another tank that broke. I just need a bottom and I have a tank.


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Unread 03/05/2020, 10:27 AM   #9
oreo57
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Originally Posted by Jade5051 View Post
The reason I'm using 1/2" glass for the sides is because it's scrap glass from another tank that broke. I just need a bottom and I have a tank.
I get stuck in my head...

Using thinner glass for the bottom (regardless of safety factor) is just psychologically unacceptable..

14.8 (sides) and 8.5 (bottom) safety factors for 1/2 all around..

1/4" (6mm) ..nope
5/16" (8mm) It is not common in US. nope..
3/8" (10mm) pick one
1/2" (12mm) pick one


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Unread 03/10/2020, 01:39 AM   #10
H2oGarden
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3/8 if supported, 1/2 if not supported.


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