How much water volume will be safe by 5mm thick tank

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naungnow

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Sep 28, 2010
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Hi all,
Recently I finished the building a new tank that made by 5mm thick glass. The tank dimension is 42" x 18" and 22" high. I made double glass sealing in every seal area (check in photo). After finishing it, I could not decide that how much water level should be high safely in that tank. If there someone who can advise, help me please........
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As others have touched on 12.5 is recommended but I'm sure you can safely get away with around 15 if you have braced the top. Those calculators have some error as to produce a result on a very safe side.

If I were you I would have flip it and made one of the front panels the base so your left with a 42"x 22" and 18 inches high with that glasses thickness. You would have a panel that protrudes above the 18 inches but that would be great fish tank dimensions.

If you can get the glass cut I would do it that way and have one of the 42" inch panel cut down to 18 inches and have strips made from the 42" inch panel to euro brace it.

At a height of 12.5 your water volume is 40 gallons but if you have the front panel as the bottom of the tank as 42"x22" and 18" high then your water volume is 64 gallons filled 16 inches high which those dimensions are MUCH more usable for a flowerhorn. In fact those dimensions can EASILY house a full grown fh for life.
 
That is really thin glass even for 12.5" deep. You have a span 42" across, that glass is going to be very weak. It may not give out from the water, but anything hits it too hard, fish included and it may crack. I sure as heck wouldn't have that in my house.
 
fishguy306 said:
That is really thin glass even for 12.5" deep. You have a span 42" across, that glass is going to be very weak. It may not give out from the water, but anything hits it too hard, fish included and it may crack. I sure as heck wouldn't have that in my house.
Click to expand...

There would actually be less pressure on the glass at 12.5 with the new dimensions as the pressure is distributed throughout a larger surface area.
 
at 5mm, the side glass have nor problem handle up to 18'' or water for the most situation, I agree that if you have braced on top it would be safer. But for the bottom piece of glass, 5mm in a 48''X18" is not safe for water higher than 10'' and in my experience the bottom glass will start to crack when water pass 14'' most of the time. The bottom glass is needed to be at least 10mm for that footprint.
 
naungnow said:
Hi all,
Recently I finished the building a new tank that made by 5mm thick glass. The tank dimension is 42" x 18" and 22" high.
Click to expand...
The tank may be too large for 5mm thick glass. There is no mention of the type of glass utilized... standard, plate, or tempered.
In any regard, I wouldn't house a fish of that size in any tank with less than 3/8" plate glass. There is the high probability that the stress from water pressure on such a thickness (or more aptly - thinness) combined with an impact from any fish of good size might not only crack it, but fully rupture it. You might consider adding a top frame with center brace all of polycarbonate, but that still leaves you with a risky setup.
 
Danielcho said:
There would actually be less pressure on the glass at 12.5 with the new dimensions as the pressure is distributed throughout a larger surface area.
Click to expand...

WRONG! WRONG! WRONG!
Pressure is a factor associated with depth, not surface area!
The glass is not rigid, but flexible; hence the bowing of the front pane easily noticeable on any standard 55 gal tank which by-the-way is 22" high and almost always 5mm tempered glass. It is this "larger surface area" which is of immediate concern due to the amount of flexing or bowing that a 42" length of non-tempered 5mm glass will do! This aspect of the design is exactly why everyone has expressed concern and why many have recommended center bracing it. As for the bottom being only 5mm also. Easy fix...
Get a depth guage and find out EXACTLY how recessed the bottom is from the bottom of the frame (if it even has one). A set of highly effective and inexpensive braces may be made with 1/4" slats of acrylic epoxied to the underside in concentric rectangular pattern or X pattern cross the center with a few parallel strips (V's from each of the sides) for added piece of mind.
The height of the strips should be just a hair less than the recessed depth measurement taken earlier in order to accommodate the epoxy fill.

And FYI... At 48" long (6" more than the tank of concern), a standard 55gal has 5mm tempered glass on all sides and bottom glass too.
A standard 40B also has thinner bottom glass than the sides and again...Tempered.
If he used tempered, ok... salvageable... if not - it's a dangerous setup - especially for the occupants.
 
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