Plywood glass calculator?

Squirtle919

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Sep 5, 2011
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Hello all, was wondering if anyone has a calculator for plywood aquarium viewing panels?

I have had a google but can only find normal calculators, figured because the wood shell is taking all the pressure mainly + the seams are on the wood not glass so... why cant I use a thinner sheet of glass?

I am thinking 10 x 5 x 3 (maybe 4 might be weird with panels I have but.. ) but I want to leave at least 25+ cm from the base before starting the window so if the tank was to leak it wouldn't completely drain.

19mm is recommend for a full glass tank, was hoping to use 10mm 6x2 panels or 2 x 10mm 4x2 panels with a center support?

Would this work or??? I cant see how the glass can break away from the seam as can occur with a glass tank, my only concern is the glass could actually shatter due to the pressure of water but unsure how this is figured out?

Any advice would be great. thanks all!
 

Dieselhybrid

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It will most likely shatter. Use thicker than recommended. Not thinner.

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Jag586

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So you want a 4 ft tall pc of glass and it should be 19mm and you want to use two 10mm? It won't work the only way to use thinner glass is to make it shorter the glass thickness is dependent upon how tall it is so maybe make it 3 ft it'd be thinner


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Squirtle919

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No the calculator I have is for all glass, I believe 19mm is required as its all glass but with plywood the glass is not taking any load on the seams as this is wood? I know if it was all glass 19mm is a must but thats factoring that the glass is taking all the pressure on the seams which it will not be doing... the woods going to be taking most of the pressure.

The windows only 2ft tall.. I dont want a window from the base to the top if it does pop bye bye to all the fishy, if theres wood 1-2 ft from the base to window if window pops the tank will only drain to that point allowing the fish to remain in water.

I have found a few threads on saltwater sites going over it but still confused they state you can go thinner but dont recommend how to calculate it. Below..

"That calculator doesnt take a few things into consideration when building with plywood. One is the abundant bracing type reinforcement that plywood offers, the other is the fact that the glass is usually not bearing the pressure at the bottom seams, that is taken by the plywood. So in actuality you can use thinner glass than any calculator will show. This is because they are planning on using all glass, and plywood is tough to account for. I know of a few 30" tall plywood tanks that use 1/2" glass. You can do this because plywood is infinitely stronger than glass, and the bracing around each pane, and the fact that the glass doesn't bear pressure at the seams -esp the bottom where the pressure is highest"

^ this is how I am looking at it also I cant see any reason to use the same recommended thickness for all glass when using plywood it just dose not make sense
 

wednesday13

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Look into builds for koi ponds.. many people dont use the appropriate thickness for a build as ur referring too. The same goes for acrylic, but acrylic will bow before it shatters. Personally i wouldnt chance it with glass, but im not comfortable with it. with acrylic and the right support 4' can easily be achieved in 3/4"-1" where as recomendations with regular calculators are at 1-5"-2" for the same height.


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Jag586

Piranha
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If I'm not mistaken you just account for the window size so a 2 ft tall pc of glass only has to be x mm thick the frame doesn't matter or seams in this case as the glass will bow out and break if too thin

So use the calculator for 2 ft not the 4 feet of the whole tank but just the size of the window


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PGill

Feeder Fish
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Mar 20, 2012
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You mentioned the seems but the thickness isn't for the strength of the seems on an all glass tank. The thickness calculator is calculating what pressure the glass itself can sustain. When you're calculating the thickness just use the height of the water column that will be on the glass. So if the water height from the bottom of glass is 24" than 1/2" thick will be plenty regardless of the over all depth. Take into consideration that you're probably only going to have 21" or 22" of glass exposed, the rest will supported by the frame of the tank on all four sides which in theory should give a little higher safety factor I would think. Pretty much what Jag586 said.
 

Squirtle919

Plecostomus
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Sep 5, 2011
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Thanks guys.

Yes I have seen lots of koi people use much much smaller glass and 0 issues years later. Acrylic would be nice but its too much maintenance + its double the cost of glass down here even at my rates :( glass also gives me a good work out lol!

I see what you guys are getting at though, thanks! I have always looked at it different in regards to thickness of glass.

So I am fine to use 10mm then, safety factor of 2.5! I am going to use a pond liner most likely as I believe its much more "long term" then coating so the window will be encased in a steel frame most likely, quite confusing figuring this part out... pretty much thinking stainless steel c channel then run the liner in and out (glued to steel) then window goes over liner and adhesive again then cut liner just after the window.

Also found a local liner that can be welded to any shape :)

Thanks all for the help.
 

greenterra

Blue Tier VIP
MFK Member
As long as the lower part of your tank is solid and can't flex. The height that matters for your calculations is from where the bottom of the window starts(unsupported) to the top waterline.
 
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