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Old 11/04/2017, 07:40 PM   #1
fullmonti
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glass thickness?

How thick would the glass need to be for a 12x12x24" tall rimless tank? I was thinking 1/4" & if that would be iffy use 1/4" tempered glass. I was going to use a 10X24 cylinder vase & ordered it & it came in broken mostly because the glass was thiner than window glass. I'm making a tower tank for my NPS, with some photosynthetic corals at the top of the tower.


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Old 11/06/2017, 02:30 PM   #2
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http://www.miraclesaquariums.com/201...-PRICELIST.pdf


Just from looking here... 3/8" will work, if anything it'd be bigger then needed.


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Old 11/06/2017, 03:17 PM   #3
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I would have no doubt at all 3/8" would be more than enough. I am hoping someone with tank building experience would know if 1/4" would be a safe bet. I really think 1/4" would be fine but would feel better if someone with this expertise could share.

Thanks
Jim


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Old 11/06/2017, 04:26 PM   #4
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No 1/4" is not sufficient for a rimless of that size..
Its quite a bit under the typical safety factor for a rimless tank.. (like 4 vs 7.8)
go 3/8 or 9mm


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Old 11/06/2017, 06:49 PM   #5
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If you would could you explain what (4 vs 7.8) is and how to calculate what is needed for different size tanks? This has come up before and never sure what is needed.


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Old 11/07/2017, 05:49 AM   #6
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https://en.wikipedia.org/wiki/Factor_of_safety

Shoot for ~4 (3.8) for rimmed/eurobraced tanks and 8 (7.6) for rimless tanks.. Its whats been used over the years and proven to work..

Designing a rimless tank with a sf of 4 makes it far more likely to fail and the added cost of the correct glass is cheap compared to the potential damage the water can do..
But its your tank/your life.. This is one of those decisions though that going cheap could cost you far more.. Its just not a smart move to tempt fate here..

There is a simple excel calculator floating around that someone has done to do all the math for you..


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Old 11/07/2017, 03:31 PM   #7
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Thanks for the follow up but I and I think others would benefit from a little more conversation on this subject.

No doubt 3/8 is safer than 1/4 and by the same logic 1/2 is safer still than 3/8. I am not arguing I just find it hard to understand how a thin frame of plastic around the factory made tanks makes it possible to use much much thinner glass. For example Aqueon makes a 13 1/4x13 1/4x20" tall (they call it 24" tall but the water level is only 20" tall the rest is the hood) The glass on that tank is 1/8. I called Aqueon to see if it is tempered or not and it is not. The hood being built into the plastic rim does make it more substantial than a typical rim but hopefully you see where I'm headed. In general we live in a place where if a factory made product is inferior or unsafe they don't stay in business long, so I assume the factory made tanks have a reasonable safety record. So how can a little plastic frame make so much difference?

When you/they talk about safe and possible failings are you talking about the glass its self breaking or the silicone turning loose?

None if this is about the little extra cost of using thicker glass, lord knows there is very little about reef keeping that is cheap anyway. I could bye the Aqueon tank and stand for less than the materials would cost to build the tank I want and may end up doing that but really would like to know more about all this for the future and I bet others would too.


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Old 11/07/2017, 05:22 PM   #8
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The safety factors I've stated are whats considered "very safe" by most standards..

Companies/individuals can certainly choose a smaller safety factor as 1x is technically all that needed (in a perfect world) according to the math to ensure that the stress/strains placed on the glass do not exceed their limit/breaking point..
But nothing is perfect and you build in safety factor to ensure that if there is a slight thickness difference in the glass or that this run of glass has some impurities that effect its overall mechanical properties are reduced, or whatever don't cause a failure to occur..

And the calculations for a tank are 100% about the glass and have nothing to do with the silicone used.. Its all about the properties of the glass..

Now I will say that the plastic trim absolutely adds strength because its not just a flat piece of plastic in one plane.. its designed such that there a few "jogs" to it to strengthen it in multiple directions.. Once its restrained by the glass/silicone in the other directions it takes a considerable amount of force to deflect it horizontally.. Many of them also have a "strap" built in that goes front to back and may have multiples depending on the tank length.. That adds a ton of strength..

I bought a 120G 6ft tank from someone that removed the trim because they wanted a rimless tank.. When you sighted down the tank from the end the glass bowed out a good 2-3" on each side or more.. But he had it like that for 2 years and it didn't fail.. But it was bowed out a crap load and no way in hell I would put that in my house.. I sure as heck did not give him asking price after pointing all that out.. and got it dirt cheap..

I took it and replaced the rim and there was ZERO bow to the glass after.. So yes.. the plastic trim does add strength and prevent the glass from bowing quite a bit.. A lot more than you think clearly...

Use 3/8" if rimless or 1/4" and eurobrace it..


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Old 11/07/2017, 09:12 PM   #9
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All righty then

Thanks again


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