I'm in the middle of a plywood build. 12 feet long, 35 high, 26 wide. The front will consist of 2 annealed panels, 66 long x 32 high. Initially, I planned for 1/2" glass. The glass will have 2 inches of bracing on all sides bringing my total viewing height of the glass to 28" tall. It seems the general consensus is that anything over 31 inches needs 3/4 glass, but I am unsure if that is referring to total height, or since the non-braced span will be only 28 inches, that the 1/2 inch glass will suffice. Thanks for the time.
Total Height or Viewing Area Thickness
- Thread starter Deep South Frontosa
- Start date
Welcome to MFK!
The height you need to use is the distance from the lowest point that water can be viewed at the bottom, to the highest point the water reaches in the tank, (whether viewable, unviewable or supported) at the top. So, the distance from the water surface to the viewable water at the bottom.
For 31" tall, 1/2" glass will be unsafe. It should be 3/4" although, with new, high quality glass, very good bracing, and perhaps luck, one can possibly get by with 15 mm. For 28" tall, 13 mm will provide a minimum safety factor (2.5), although for a tank that size, I'd be looking for the more common target of 3.4, which would be 16 mm.
Using low quality or previously used glass (especially store front or office window glass), would invalidate those numbers as the glass is likely to contain microfractures from mishandling or simply repeated temperature fluctuations.
Imo, the larger the tank, and thus the greater amount of damage the release of water might cost, the greater the need to hit the more common target of 3.5.
Not being an engineer, I have no information on annealed glass being used in the manner you've described. Apparently, most people don't use it, which makes me wonder if it's unsuitable doe to clarity, availability or strength, or perhaps, some combination or all three.
The height you need to use is the distance from the lowest point that water can be viewed at the bottom, to the highest point the water reaches in the tank, (whether viewable, unviewable or supported) at the top. So, the distance from the water surface to the viewable water at the bottom.
For 31" tall, 1/2" glass will be unsafe. It should be 3/4" although, with new, high quality glass, very good bracing, and perhaps luck, one can possibly get by with 15 mm. For 28" tall, 13 mm will provide a minimum safety factor (2.5), although for a tank that size, I'd be looking for the more common target of 3.4, which would be 16 mm.
Using low quality or previously used glass (especially store front or office window glass), would invalidate those numbers as the glass is likely to contain microfractures from mishandling or simply repeated temperature fluctuations.
Imo, the larger the tank, and thus the greater amount of damage the release of water might cost, the greater the need to hit the more common target of 3.5.
Not being an engineer, I have no information on annealed glass being used in the manner you've described. Apparently, most people don't use it, which makes me wonder if it's unsuitable doe to clarity, availability or strength, or perhaps, some combination or all three.
Thank you for the insite. Briefly checking online prices, 3/4 is almost double the price. May be easier to redesign the tank to be more shallow. It will be fully euro braced with multiple across the top braces which will help out the safety factor, but that height still isn't the best scenario.
As for annealled, from my research I found it to be more common than tempered in these applications. Reason being that the strength isn't worth the catastrophic, no time to recover, blow out of a tempered tank. While the annealled is weaker, the crack should in theory give you some time to salvage some water/fish and drain some water instead of the instant tsunami of a tempered failure.