Small Tank Specs

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Hi hennie
I'm going to build a small tank to sit beside my main tank as a sump extension for my skimmer(sump space issues). I was thinkin something along the lines of 600(H)X350(W)X400(L). maybe a bit smaller, but thought i would post the largest dimensions i was thinking of using as a smaller tank would then be of lower risk.
The glass thickness calculator suggests a glass thickness of 6mm, which i think is adequate aswell, and it suggests a bottom glass thickness of 13.9. That is pretty thick, but if i put 6mm in the base section the safety factor goes down to 0.7. I guess i can buy two base panes of 6mm thick and then glue those two together to make twelve, how would i need to go about this or would a 6mm only base still be ok even though the safety factor is 0.7? how prone to a crack or something along those lines would i be?
 
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I must rush, and will answer in more detail at a later stage.

would a 6mm only base still be ok even though the safety factor is 0.7?
No, a safety factor of less than 1 is an indication that the glass will break VERY easily, and I would not consider it.

Your problem is with the 600mm height. Consider that even if the tank is 600 high, your water level will only be around 550 - re do the calcs with that figure.

I guess i can buy two base panes of 6mm thick and then glue those two together to make twelve
Two 6mm panes will not be as strong as one 12mm pane. I would suggest that you try to get a 10mm pane for the bottom - 10mm is not so expensive, and is more readily available.

Hennie
 
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Your problem is with the 600mm height. Consider that even if the tank is 600 high, your water level will only be around 550 - re do the calcs with that figure.
Hennie
i did the calculations with that height because that is the height of the water, i forgot to increase the glass size to account for this but basically that is the water volume. I need to drill a hole in the side of the tank for an overlflow, which pane of glass would be the safest one to drill into? How far below the top of the glass do i have to drill for it to be safe? I will be getting the glass company to drill all the holes so it will be done properly and not by me, and for the trouble of having reduced the strength of the structure, should i just build a small over flow? if that would be the case the overflow would then have to go on the shorter side(ie not the length)

After taking proper measurements of my needs of the tank it comes to 620(H)X540(L)X380(W).
 
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should i just build a small over flow? if that would be the case the overflow would then have to go on the shorter side(ie not the length
Even the shorter side (width) of the tank will allow more surface water to overflow than a hole drilled in a pane. I personally have a weir overflow across the one side of my tank, and can vouch that it works very well.

Even a professionally drilled hole will still result in weakening the glass it is drilled in, so I would recommend that you rather go for the weir-type overflow.

Hennie
 
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hennie, what do you think of perspex? do you think this little tank can be made out of perspex with a decent degree of safety? I've managed to get in contact with a very good fabricator as he is doing my skimmer holes etc, and he says it would be alright. 5mm be alright? to be safe i would put in some euro bracing
 
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hennie, what do you think of perspex? do you think this little tank can be made out of perspex with a decent degree of safety? I've managed to get in contact with a very good fabricator as he is doing my skimmer holes etc, and he says it would be alright. 5mm be alright? to be safe i would put in some euro bracing
Its gonna cost more. perspex is expensive scuba
 
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hennie, what do you think of perspex?
I really don't have any personal experience with Perspex tanks, so I really cannot comment. At a wild guess, I would think that 5mm Perspex will not be sufficient for a 600mm water pressure, even with bracing.

Perhaps someone else with experience can comment?

Hennie
 
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thanks hennie. i saw a tank built out of perspex today when i went to the fabricator. the bonds seemed very strong, but it did flex a little. but it was only three mil perspex. i think that if i brace down the body of the tank too i might get away with it but i was assured it would be ok. i thought it may be nice, if this is all cheaper than glass that is:) so i will let you know:)
 
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well i hoped they would know the difference cause i don't. but after finding out the prices i'm just goin to go with the glass:) will look nicer i think when i put black silicon on it:)
 

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on a side note, where can i find these "calculators"? and anyone got a pic of euro-bracing?
 

dallasg

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thanks
 

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