what glass to be used on a aquarium? tempered?

fishpets101

Exodon
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hi! im doing a 300 gallon (68 by 30 by 30 inch) aquarium and i was wondering if i should use regular glass ( cost affective) or toughened/ tempered glass ( very expensive) my LFS told me that regular glass breaks easily and can actually kill people if broken! on the other hand i found no info that regular glass is bad and actually found info that tempered is very dangerous! what do you think?
 

skjl47

Potamotrygon
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May 16, 2011
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Hello; Let me first say I am not an expert on glass and I only have personal experience with one homemade tank. I do know a small amount about the tempered glass and plate glass in terms of how they break.
The homemade tank was a 125 gallon with plate glass set in an angle iron frame. The glass did break after many years of use but it was not dangerous. There was a top brace of angle iron across at the center of the tank. The fatal flaw was in not using stainless bolts and nuts to attach that cross brace to the angle iron frame. Over time the small threaded bolt that held the brace had rusted. The rust slowly built up and pressed against the edge of the plate glass. A crack eventually started and ran down the back pane of glass. I found the tank almost empty of water.
I guess if somehow plate glass was impacted and shattered there will be sharp shards of glass. Those shards can be long with razor sharp edges. I have broken plate glass many times and it does make such shards.

I was given some glass out of a sliding patio door. I had a notion to cut it down and make a tank with it. Removed the frame as it was a double pane door. When I started to cut it my regular glass cutter was not making a good scratch. I decide to start on an edge of the glass with a file to try to start a decent scratch point.
I was wearing heavy gloves and eye protection but not hearing protection. I have had plate glass have chips and small pieces fly about so always wear protection. Anyway, all of a sudden as I filed on the edge of the sheet of glass the size of a sliding door the entire pane shattered into thousands of small pieces. There was a loud boom. Not as loud as a gunshot but still plenty loud. The small pieces were maybe the size of a nickel, dime and quarter. many had flown off for a small distance, maybe three or four feet. A lot of the pieces were still loosely together but not attached so much as just slightly held in place by the irregular shape.

It took a while to sweep up all those pieces. And I still to this day have three sheets of what turned out to be tempered glass leaned up against the side of my house. I may someday find a use for it but the use will have to bee in the size it currently is. This tempered glass may be stronger than plate of the same thickness but what I have is thin. I do not know if it is strong enough to use as is for the size it is in an aquarium.

Here is my take. If you use tempered glass it will have to be made in the exact size and thickness you plan to use. It is very able to handle temperature extremes. I have used tempered glass in labs and have some tempered glass cookware. I cannot say for sure it is actually stronger than plate glass in terms of the type of strength needed in an aquarium, but I expect so. My guess is tempered glass will take a lot of certain types of abuse better than plate glass and if somehow it's limits are reached it will shatter into hundreds or thousands of small pieces. Those multitude of small pieces are not as dangerous as plate glass which is why it is often used in sliding doors where there is a chance of a person falling thru it. That said if aquarium tempered glass ever shattered the entire volume of water will dump all at once rather than just leak out as with my plate glass tank.

There may be a type of tempered of plate glass that is safer to use. Automobile windshield glass is two layers of glass with a sheet of clear plastic in between. That way it holds together better when impacted and does not throw the long cutting shards so much. Maybe a tempered glass that wont shatter into thousands of pieces or a plate glass that is laminated like windshield glass. By the way laminated windshield glass can be cut. I have seen it done on PowerNation Episodes.

I would probably use plate glass if building a tank. I will follow this thread in the hope of learning some new stuff. Good luck.
 
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Hendre

Bawitius
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Glass cracks, tempered glass shattered. Almost all tanks are built with regular iron glass, and some with low iron glass if you have a lot of money. For a tank that big definitely go with nice thick regular glass.
 
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Backfromthedead

Redtail Catfish
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Use standard float glass, aka annealed glass when building tanks. There are several reasons for this but the biggest is the explosive nature of tempered glass under pressure. Compare a slow dripping leak that could possibly be repaired to 300 gallons of water on your floor. In my mind this is the potential difference between annealed and tempered glass (respectively).

It seems that many amateur builders will attempt to skimp on glass thickness under the impression that a thinner piece of tempered glass will equate to a thicker piece of annealed since tempered is stronger. Big mistake ime.

The mass tank manufacturers that use tempered glass build their tanks to such dimensions and tolerances that glass failure usually isn't an issue, like the standard 125 or 75 gallon tanks commonly found in big box stores. But considering that you're building a tank of nearly 300 gallons and 30" tall, you'll want to use the thickest annealed glass you can afford.
 
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Dalfrey86

Piranha
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Pro tip, you can cut laminated tempered glass... think a windshield... just not advised because metal on tempered glass may cause explosions.
Learned this little trick when I did my first chop top on a shoe box Chevy sedan. 3 windshields later and a few stitches I got it cut, but won’t be jumping at the chance to do it again.
As far as cost is concerned, what’s cheaper? Water remediation or buying proper glass? Odds are it’s going to be the glass hand over fist.
To echo Hendre, buy the iron glass, you will be happier with the clarity over standard plate glass. As plate glass may have imperfections in an undesirable place. Plus there is going to be a changing load onto the glass during WC, therefore it’s better to build with this factor taken into account instead of just thinking of initial cash outlay.
 

fishpets101

Exodon
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Jun 21, 2020
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Use standard float glass, aka annealed glass when building tanks. There are several reasons for this but the biggest is the explosive nature of tempered glass under pressure. Compare a slow dripping leak that could possibly be repaired to 300 gallons of water on your floor. In my mind this is the potential difference between annealed and tempered glass (respectively).

It seems that many amateur builders will attempt to skimp on glass thickness under the impression that a thinner piece of tempered glass will equate to a thicker piece of annealed since tempered is stronger. Big mistake ime.

The mass tank manufacturers that use tempered glass build their tanks to such dimensions and tolerances that glass failure usually isn't an issue, like the standard 125 or 75 gallon tanks commonly found in big box stores. But considering that you're building a tank of nearly 300 gallons and 30" tall, you'll want to use the thickest annealed glass you can afford.
thanks a lot! by the way i'm going to be using 12mm glass. is that okay?
 

Backfromthedead

Redtail Catfish
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thanks a lot! by the way i'm going to be using 12mm glass. is that okay?
I would recommend thicker glass on the long sides and bottom. Most tankmakers would use at least 15mm front, back, and bottom with that height. 12mm would work for the short sides ime. You'll definitely want to plan for some sort of bracing on the top the tank too.
 
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fishpets101

Exodon
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I would recommend thicker glass on the long sides and bottom. Most tankmakers would use at least 15mm front, back, and bottom with that height. 12mm would work for the short sides ime. You'll definitely want to plan for some sort of bracing on the top the tank too.
i'm doing both a regular brace and a euro brace
 
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