Glass thickness help please

[Not another new tank]

Hi all, in the Uk plywood tanks seem to be very uncommon indeed yet in the US they seem a regular occurrence hence I need a lot of advice please. It only a small tank due to the space I have in that area. its going to be: 66" long x 40" deep x 30" wide. I been watching the youtube vids and I'm happy to build one strong enough and use what everyone seems to use to seal it eg: Pond shield again made in the US

Now what thickness glass are we looking at here??? I'm going to overlap the wood by 4" all-round to be on the safe side. Should I use laminated and toughened which I can get a piece of low iron 13.5mm for £450 or should I go 15mm float or will I need a thicker glass?? I've seen some builds bigger that have used just 12mm float which scares me. I really need some help people here. Any advice would be most welcome, put me right people.

 

[esoxlucius]

I'm from the UK and i'm building a plywood tank early next year hopefully. I'll be checking out the many glass thickness guides that are readily available and then when i've found the reccomended thickness, i'll get a piece that's thicker!! I'm absolutely anal when it comes to aquariums, complete overkill is the way I think. And yes, i'm with you on the 12mm thing, that is ridiculous, i'd never sleep at night!

I don't think i'll be going as deep as 40" like you. That will require 15mm as a bare minimum in my book, whether you need to go as far as toughened or laminated I couldn't say.

 

[Not another new tank]

Thank you very much for the reply. How deep could you go with 12mm or 15mm normal float?? I realise that the width of the tanks also has to be taken into consideration in calculating the water pressure on the glass. I priced up normal float today: a 5'x3' piece is 12mm = £109 + vat and the 15mm is £200 + vat. So the 15mm is double the price but thats what I'm thinking of using.
Also if the tank is 40" deep the water level would be around the 36" mark only. Now as long as the glass is supported all the way around by a frame and supported at the bottom with a 2x3 I assume the weight of the glass does not impact upon the silicon holding it?? Also I'm thinking that water pressure would be working for me for once in keeping the glass pushed against the silicon??? A 5 x 3 15mm piece is heavy as you know, will it be ok in a plywood build???? Oh would you pay extra for iron free?? Sorry I have so many questions, I'm really out of my comfort zone with this build.

 

[TwoHedWlf]

I don't think laminated is usually used because it's significantly weaker than the same thickness single pain glass. Toughened usually isn't used because you can't normally get it in exactly the right size. Probably more of a tendency to catastrophically shatter too, compared to float glass.

Plugging it in to this calculator: https://www.easycalculation.com/measurement/aquarium-glass-thickness-calculator.php

With a safety factor of 3.8 which is commonly recommended gives you a result of 23mm thick glass.

15mm only gets you a 1.5 safety factor and something just bumping into the glass will break it. 12mm is exactly 1.

When you have people bumping into the tank, big fish probably running into the glass, occasional rock or something slipping and hitting it. Possibly scratches and damage to the glass when installing. You probably want to stay with 3+ But at least in the UK you don't have to worry about earthquakes.

 

[Not another new tank]

Great reply, thank you very much indeed. From the info you provided it looks like the height will have to be reduced. I'll keep putting the measurements into the calculator and see what we come with. Once again thanks. No, no earth quakes here oh the safety factor used in the UK is only 2.5, do you think thats down to issues such as you mention???