ChrisP Posted September 28, 2004 Report Share Posted September 28, 2004 I have used Warren Stillwell's glass calculator to calculate glass thickness for my planned 1208mm/48 in(long) by 500mm/21 in (wide) by 750mm/30 in (high) aquarium (BUT it will only be filled to 600mm/24 in depth - remaining clearance for overflow, space between canopy lights and surface, etc.). It gives me a thickness of 12mm (1/2 in) for the sides, and 15mm (5/8 in) for the base. I assumed that was without braces. But in talking to my LFS, they insist you cannot build a 4ft tank without bracing all around it and across its centre (using 2 in wide glass strips of the same thickness - 1/2 in - as the sides). Does anyone know whether Stillwell's calculations assume braces or no braces? Is it possible to construct a 4ft by 21 in all-glass aquarium, filled with 2 ft of water, without any bracing at all? Or at least, without a centre brace? And what glass thickness would I need to avoid braces (I know this will be a more expensive option, but I just hate braces!)? Lastly, in constructing the tank, should I use standard float glass or toughened (safety) glass? The latter is stronger, but shatters into a thousand pieces if struck hard, whilst standard float is more likely to crack (giving time to siphon out water & relocate at least some livestock). Many thanks in advance for your help. Quote Link to comment Share on other sites More sharing options...
livebearer_breeder Posted September 28, 2004 Report Share Posted September 28, 2004 all i no is that toughened glass is more expensive and you can not cut it, you will have to get it pre made for you at a glaziers, and i would doubt that the toughened glass would shatter into a million peices as the the water pressure would have to be very high! Cheers Shae Quote Link to comment Share on other sites More sharing options...
Brianemone Posted September 28, 2004 Report Share Posted September 28, 2004 i think 10mm would be fine for a tank that size Quote Link to comment Share on other sites More sharing options...
livebearer_breeder Posted September 28, 2004 Report Share Posted September 28, 2004 i think the lfs is telling u a load of bull actualy chris, i assume there trying to make you spend money thats not nessecary, that is usually there way! i would think that 10mm glass would b fine for the whole tank! and i would never use a 15mm thick glass for a base, not sure about the braces! but i agree there ugly! i would think you should be fine considering your only half fulling the tank! Cheers Shae Quote Link to comment Share on other sites More sharing options...
dan_from_nz Posted September 28, 2004 Report Share Posted September 28, 2004 you might be able to get away from a centre brace but you would need to get them to cut the centre out of a sheet of glass so you had a full surround of about 2in. (this gives much more support than 4 2in. strips running around) and i would go up to 14mm glass for the walls if you were going to do this. In my small amount of experience with glass I have found tempered glass to be amazingly strong I had 400mm x 400mm peice of 6mm tempered glass that i could hit with a hammer or throw down on the concreet without breaking, in fact one time it chipped the concreete and not a mark on the glass (this is only impactual strength though i dont know what it is like with constant pressures). Unfortunatly it can't be cut so it is very expensive buying at a cut rate (i think glaziers in New Zealand charge about $180.00 per S.Q.M although i managed to get it as low as $60.00 /S.Q.M) There is also diferent types or clarities of glass available normal glass can look quite green aparently compared with starfire glass the link below is an aussie forum that discusses some tanks being built http://www.masa.asn.au/rtaw/showflat.php?Cat=&Board=General&Number=105213&page=2&view=collapsed&sb=5&o=&fpart=1 Good luck Daniel Quote Link to comment Share on other sites More sharing options...
cees Posted September 29, 2004 Report Share Posted September 29, 2004 I have used Warren Stillwell's glass calculator .... Welcome ChrisP, For those of you who might not know about it. The glass-thickness calculator can be found here. http://www.fnzas.org.nz/glassthickness.0.html i think 10mm would be fine for a tank that size i would think that 10mm glass would b fine for the whole tank! Guys, please don't think. Get the facts, use the calculator !!! ChrisP : I'm sure Warren will comment on this. What are the numbers when you calculate it for 600mm rather then the 750mm. If you only fill to 600mm than that's what you should be using perhaps. Quote Link to comment Share on other sites More sharing options...
Pies Posted September 29, 2004 Report Share Posted September 29, 2004 I spoke to Warren about this exact same question a few months ago. He told me that the calculator assumes tha tthe tank is perfectly braced (infact I think he said that the glass is assumed that its in an angle iron frame). To brace or not to brace. Easy, brace. Pies Quote Link to comment Share on other sites More sharing options...
Ira Posted September 29, 2004 Report Share Posted September 29, 2004 There aren't really any disadvantages to bracing as long as you're smart, they don't have to be too big so they get in the way. So...Yeah, I agree with Pies. Quote Link to comment Share on other sites More sharing options...
Matthew Posted September 29, 2004 Report Share Posted September 29, 2004 My four foot tank is made from 10mm glass and I have no problems with it. It has three braces (two either side- about 4 inches-and one down the middle- about 6 inches). As for the toughened glass question. It does have a higher breaking resistance, but when it breaks it shatters. It is also easy to break by tapping the side of the glass, probably easier than float glass when hit on the side. My recommendation would be to go with float glass, it is cheaper, and the mess is significantly reduced if there is breakage. Quote Link to comment Share on other sites More sharing options...
ChrisP Posted September 29, 2004 Author Report Share Posted September 29, 2004 Thank you all for the advice. Just to clarify a couple of points. The reason for my confusion is when you enter this tank's dimensions (and I am entering water depth - 600mm - not glass height - 750mm) into the GARF tank calculator (http://www.garf.org/tank/BuildTank.asp), it gives you a recommended glass thicknesss of 3/8" (10mm) for all four sides plus base. With bracing around all top edges, but no brace across the centre. When you enter the dimensions into Warren's full equation (http://www.fnzas.org.nz/glassthickness.0.html), you get a recommended glass thickness of 12mm for the sides and 15mm for the base. HUGE difference in cost (and significant difference in viewing clarity). So I thought it might be because Warren was assuming there would be no bracing. But Pies has spoken to the man himself, and says there's bracing all around plus across the centre. BTW, if you use Warren's Excel spreadsheet to do the calculation for you (http://www.fnzas.org.nz/uploads/media/G ... sCE_02.xls), it gives you 12mm for all glass sheets. I guess this is all down to safety factors, but since I have no idea what safety factor I should set, I remain totally confused! 10mm all round? 10mm for the sides, 12 mm for the base? 12 mm all round? 12mm for the sides, 15mm for the base? And just in case this changes anyone's recommendations, there will be a wooden frame (12mm thick by 33mm high) sitting on top of the glass with 6mm thick MDF panels screwed/glued to the frame and jutting down 150mm around all four sides. This is for cosmetic reasons (to conceal the air space at the top of the tank), but if it is a snug fit around the glass, it should provide some extra stiffening. The second point of clarification is about toughened glass. I have used a lot of it for glass doors, shelves, etc., and like Daniel and Matthew, I have found it to be incredibly strong (i.e. both stiffer and more resistant to breakage than ordinary glass), but very prone to little pieces breaking off the edges if struck on the edge. If you do manage to hit it REALLY hard on the face, it breaks into a thousand pieces - instantly (there is NO in between - either it is completely unaffected, or it completely disintegrates). Never having used it in aquaria, I was wondering whether that extra stiffness would reduce bowing and hence the need for bracing, but I have no idea how it behaves under contant pressure. Any more views? Chris Quote Link to comment Share on other sites More sharing options...
Caryl Posted September 29, 2004 Report Share Posted September 29, 2004 Warren is sick after all his hard work. I am sure he will be back online soon to help you with your questions Quote Link to comment Share on other sites More sharing options...
Pies Posted September 29, 2004 Report Share Posted September 29, 2004 I am using Warrens glass calculator for my new tank, its not worth taking any chances. However I have a tank 1600Lx650Hx700W made of 10mm and its fine, it is well braced. My new tank is 2200Lx700Hx900W. Its made of 12mm glass and a doubble thickness base (22mm 12mm + 10mm). IT will be VERY well braced and has many holes drilled in it. I have seen much bigger tanks made of 12mm. My tank will only be filled to the 650mm mark though. Pies Quote Link to comment Share on other sites More sharing options...
dan_from_nz Posted September 29, 2004 Report Share Posted September 29, 2004 I think if you were to use tempered glass and it were stiffer then it would be alot more reactive to elastic potential energy (just a guess i know stuff all about science) thus making it more prone to breaking from a hit when under pressure and as you say shatter every where. I have a four foot tank (1200mm x 400nmm x 400mm water volume) that is made out of 6mm glass had two side supports @ 150mm and two centre supports @100mm so the top had 3 openings and I had snapped one when i first got the tank, It still worked fine for 6 months untill i snapped the second one and it still didnt break I left it over night and then replaced it with a new tank and we now use itas a tank for our turtle). so in theory i think 12mm would be fine but wouldn't go any less (without working things out mathmatically from an engineering perspective) remember as you increase demensions pressure increases exponentially Good Luck Daniel Quote Link to comment Share on other sites More sharing options...
Warren Posted September 30, 2004 Report Share Posted September 30, 2004 I'm all better now, - I bounce back quickly... A tank 1200 x 400 x 400 will be ok with only 6mm glass as it will have a safety factor of about 2.9 - not quite the 3.8 recommended but close enough. I don't think I need to add much, it's all been said pretty much. The glass thickness article fairly clearly explains about safety factors. It's really up to you what you chose to go with. Anything under the recommended safety factor is your risk... One of the first statements in the article says the glass is supported on all four sides (edges), so it definitely means it has top bracing... I've had a look at the GARF site. I'm currently working with them to verify the method we've both used to base our calculations. I'll let you know the outcome... As Cees said, don't think, use the calculator. I've had Pilkington Glass look at the glass thickness calculator and they've certainly not reported any problem with it. Toughened glass costs about twice as much as standard float glass. Quote Link to comment Share on other sites More sharing options...
ChrisP Posted October 19, 2004 Author Report Share Posted October 19, 2004 Hi Warren Glad to hear you're better. Been away, hence the delay in response. The question was whether a 120cm x 50cm x 75 cm deep aquarium made out of 10mm float glass (as per the GARF calculator) filled to 60 cm deep could withstand the (hopefully unlikely) eventuality of being filled to to the full 75cm depth in the event of an outflow blockage (filling to this height could accommodate all the contents of the sump). This, if you like, is my minimun safety factor. If it couldn't, would 10mm toughened (safety) glass resist this extra depth, recognising the risk of catastrophic failure if struck a violent blow? And lastly, what about laminated glass - could this combine the best of both worlds, or would it significantly reduce visibility (particularly if going for Starbrite/Optiwhite glass? Or do I have to bite the bullet and go for 12 mm float glass (or - gulp - Optiwhite) and accept the significant cost and visibility penalties over 10mm float glass? Many thanks, Chris Quote Link to comment Share on other sites More sharing options...
somethin fishy Posted October 19, 2004 Report Share Posted October 19, 2004 Using the calclulator I think I should go with 15mm glass. Proposed tank is 800L, 750H, 400W What sort of glass should I use? Quote Link to comment Share on other sites More sharing options...
Pies Posted October 19, 2004 Report Share Posted October 19, 2004 My new tank is 2200L x 730H x 950W and its all 12mm with a 22mm base. 12 looks fine to me. Brace it well. I am having my center brace made of steel rods as opposed to a glass 'strut'. For me its a case of heat issues (2000 watts of light) and light (glass gets dirty and block light, but my steel rod is smaller and less obtrusive. Good luck sounds like a nice big tank. Pies Quote Link to comment Share on other sites More sharing options...
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