fishandchips Posted October 25, 2007 Report Share Posted October 25, 2007 Hey everybody out there in fishy land. I made a great looking stand to put my 3 foot tank on but in the process of cleaning the tank out I discovered a small crack in the base. So i have decided to get a new one made, I thought about getting the old on fixed but i thought about upsizing a bit. So i am thinking of getting a tank made 915mm(Long)x410mm(Wide)x500mm(High). Now i ran the numbers through the great glass calculator and the safty factor drops to below 3 when i use 6mm glass. If i used bracing on the top of the tank would this increase the safty factor? Please feel free to suggest measurements that would make it safer or how to add bracing. Cheers Quote Link to comment Share on other sites More sharing options...
tHEcONCH Posted October 25, 2007 Report Share Posted October 25, 2007 I think you should just go to 8mm glass. Quote Link to comment Share on other sites More sharing options...
SpidersWeb Posted October 25, 2007 Report Share Posted October 25, 2007 I have bigger tanks than that (extra 20-30L or so) in 6mm, but they are braced (strip at either end, and a wider strip in the centre). Then they have braces along each edge at the bottom. Never had any problems whatsoever with them. Quote Link to comment Share on other sites More sharing options...
fishandchips Posted October 26, 2007 Author Report Share Posted October 26, 2007 So bracing is the way to go then. Anyone have plans for euro bracing i have heard that it is better then centre bracing? Also does it matter if the bracing is made out of 4mm glass? Quote Link to comment Share on other sites More sharing options...
tHEcONCH Posted October 26, 2007 Report Share Posted October 26, 2007 Bracing works fine, but personally I like 'open top' tanks so that I can slide lights back and forth, put tubes where I want them etc - but you have to make the strength up somewhere, I guess. Quote Link to comment Share on other sites More sharing options...
Barrie Posted October 26, 2007 Report Share Posted October 26, 2007 if the glass break rather than cracks, the weight would be around 180 kgs. Just think of that for a minute a sharp hunk of glass with a big weight pushing it out to where you are sitting having abeer and watching your baby play on the floor go to 8mm glass Quote Link to comment Share on other sites More sharing options...
SpidersWeb Posted October 26, 2007 Report Share Posted October 26, 2007 NB: thats 180kg pushing down, which is spread evenly over the base, thats not how much force each side is put under. Quote Link to comment Share on other sites More sharing options...
Warren Posted October 26, 2007 Report Share Posted October 26, 2007 Hey everybody out there in fishy land. I made a great looking stand to put my 3 foot tank on but in the process of cleaning the tank out I discovered a small crack in the base. So i have decided to get a new one made, I thought about getting the old on fixed but i thought about upsizing a bit. So i am thinking of getting a tank made 915mm(Long)x410mm(Wide)x500mm(High). Now i ran the numbers through the great glass calculator and the safty factor drops to below 3 when i use 6mm glass. If i used bracing on the top of the tank would this increase the safty factor? Please feel free to suggest measurements that would make it safer or how to add bracing. Cheers The glass thickness calculator assumes Euro bracing is used. Quote Link to comment Share on other sites More sharing options...
Barrie Posted October 26, 2007 Report Share Posted October 26, 2007 sorry spidersweb but I weigh 105 kgs and if i lean on something there IS weight on it and if what Im leaning on has a flaw or a weakness I go through that weakness with all my 105 kgs your calculators may well be fine but as a glass merchant, I could be hung out to dry and fined big dollas if I was to put the glass I install under the same presure Im not trying to cast doupts on a system that works but the glass simply isnt made to withstand some of the forces that we put it under. In my 40 years in the trade, I have seen the results of some horrific tank failures and almost every one has been caused by an outside force but the resulting damage to flesh is the same My last word on this subject as Im in the minority but will read your response with interest Quote Link to comment Share on other sites More sharing options...
livingart Posted October 26, 2007 Report Share Posted October 26, 2007 i agree with barrie, i was taught to think of glass as a liquid under tension so the more force you put it under, ie: hydraulic pressure, the smaller the tap to break the tension, i have gotten away with a lot in fishkeeping but eventually have come to the conclusion it is better to be safe than sorry Quote Link to comment Share on other sites More sharing options...
Fishy_Lips Posted October 26, 2007 Report Share Posted October 26, 2007 just curious is 8mm glass more expensive than 10mm glass??? Have heard conflicting info. :-? If its same price or cheaper then 10mm would be even better. jmo Quote Link to comment Share on other sites More sharing options...
Warren Posted October 26, 2007 Report Share Posted October 26, 2007 sorry spidersweb but I weigh 105 kgs and if i lean on something there IS weight on it and if what Im leaning on has a flaw or a weakness I go through that weakness with all my 105 kgs your calculators may well be fine but as a glass merchant, I could be hung out to dry and fined big dollas if I was to put the glass I install under the same presure Im not trying to cast doupts on a system that works but the glass simply isnt made to withstand some of the forces that we put it under. In my 40 years in the trade, I have seen the results of some horrific tank failures and almost every one has been caused by an outside force but the resulting damage to flesh is the same My last word on this subject as Im in the minority but will read your response with interest The difference here is you are applying your weight to a single point instead of evenly distributing it over a large area. With fluid dynamics, even though there is a large weight, it does not necessarily mean large forces on the glass - it all depends on shape. Also, the recommended safety factor for tanks of 3.8 allows for unequal stress and weak points in the glass. Statistically, tanks built using the calculator to a safety factor of 3.8 and properly supported will have less than 0.1% chance glass of failure over their life. They will also easily cope with being knocked, even by 105kg... The problem with most tanks available from pet shops or built by hobbyists on gut-feel (or past got away with it's) is the safety factor is less than 2. In this situation knocks can easily cause failure. To give you a good example, I built a 3m x 1m x 1.2m tank, fibreglass over plywood in a 75mm square steel frame. The front glass was 950mm tall, 19mm thick. When full, I kicked the front glass as hard as I could in my tramping boots to check it could withstand a decent knock. The calculator said it would survive and it did. Maths really does work, it's how all well engineered things are designed. Get the maths right and the product is perfect... Quote Link to comment Share on other sites More sharing options...
livingart Posted October 26, 2007 Report Share Posted October 26, 2007 did the same with a 2.4 x 900 x 900 i made too warren with same result no breakage, 2 years later friends horror of a kid threw a small metal truck at front glass of tank, result bang all on the floor, a half drowned kid and 1 inch of salt water on the lounge floor so now i err on the side of caution Quote Link to comment Share on other sites More sharing options...
Warren Posted October 26, 2007 Report Share Posted October 26, 2007 Yeah, any sharp point will do it... The only way to stop absolute disaster is to laminate 2 or more panes together with each pane being able to support the full load. Then if a point load cracks the outside pane the inner pane(s) will hold. There's very little that can be done to stop the law of natural selection however... Quote Link to comment Share on other sites More sharing options...
livingart Posted October 26, 2007 Report Share Posted October 26, 2007 Hi Fishandchips and Warren im not trying to be an alarmist over the thickness of your tank in our breeding setup i have some tanks i would consider probably too thin for their size, tanks are old ones as well but in the aquarium display all the tanks are thicker than needed as a safety factor for the general public and insurance purposes in the home your tank probably has less chance of taking an unforeseen knock from some outside force 10mm glass on a tank 915mm(Long)x410mm(Wide)x500mm(High) would be overkill, 8mm with bracing should suffice Quote Link to comment Share on other sites More sharing options...
PETEYPLECO Posted November 1, 2007 Report Share Posted November 1, 2007 I had one made up 750 long, 400 deep, 600 high, it has top bracing on both side with a lid front and back, this is all 8mm. Nice and strong in case I knock it or drop a rock on it while cleaning the inside. I cant think of anything worse than injury to anybody or the thought of comming home to dried up fish and a wet floor and the basment below all soggy. For the few xtra bucks go solid. Quote Link to comment Share on other sites More sharing options...
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