Help with frame for tank

afcbob · Post by **afcbob** » Sun Sep 03, 2006 9:10 pm

Am away to build a big fish tank in to my wall 6 x 2 x 2ft 12mm think glass ways about half ton fill i think. i need help noing how best to do this is size of wood? i was think 4x2"
I also would like to no what joints to use for this. am on a 1st floor flat so need the load spared over the floor
Any help would be great.

Thanks

This will be the 1st of a few post on this project.

Post by **ultimatehandyman** » Mon Sep 04, 2006 5:29 am

Hi afcbob,

welcome to the forum.

You are right, if my calculations are correct it will weigh roughly 1/2 Ton, that is some weight for an upstairs flat!

I think it might be a good idea to consult a structural engineer before you go much further as half a ton is a lot of weight to be concentrated in such a small area of an upstairs flat, he will advise you best.

On the construction side I think you should consider incorporating some large steel brackets that bolt to a solid wall, to take some of the weight. You could conceal these with your wooden frame. 4 by 2 should be strong enough as long as it is designed correctly, I would use coach bolts, with timber connector washers between the two pieces of timber that are being joined then a couple of large penny washers and a nylon locking nut. Spreading the weight across as many joists as possible is essential.

I'd check with a structual engineer first, to be on the safe side.

dirtydeeds · Post by **dirtydeeds** » Tue Oct 03, 2006 10:02 pm

afcbob, from your post, it would seem that you need a bit more detail and some idea of weights, the weight of glass is not the problem

you need to be more concerned about the weight of the water, help is at hand. 1 litre of water weighs 1 killogramme

IE a cube of water 100mmx100mmx100mm weighs one killogramme

so re meausre your tank in metric dimensions then you can accuratly weigh the water weight JUST my measuring the tank size

dirtydeeds · Post by **dirtydeeds** » Tue Oct 03, 2006 10:08 pm

in simple terms your tank is 6 foot X 2 foot x 2 foot

so the weight of water (if illed to the brim) is 6 foot = 1.22m, 2 foot is 610mm

so 1.22x.61x.61 = .45 cubic metres

.45 cubic metres = .45 tonnes =450 killogrammes (because 1 cubic metere of water weighs 1 tonne)

dirtydeeds · Post by **dirtydeeds** » Tue Oct 03, 2006 10:36 pm

from an american site glass 13mm thick weighs 6.7lb per square foot

SO 12mm thick glass weighs 6.7lb/13mmx12mm = 6.18lb/square foot

NOW convert lbs to kilos 6.18 lbs = 2.8kilos

SO 1sq foot of 12mm glass weighs 2.8Kilos

NOW convert sq foot to Sq metres .305x.305= .0915sq metres

.0915sq m, * 2.8kg = 0.199kg/sq metre

SO
tank base 6ftx 2ft =1.22*.61= 0.74m2
tank front and back 1.22*.61*2 = 1.49m2
tank ends .61*.61*2 = .74m2

so glass weight= .74+1.49+.74= 2.97sq metres x .199Kg = .59Kg

dirtydeeds · Post by **dirtydeeds** » Tue Oct 03, 2006 10:52 pm

SO adding the lot together

450 Kg of water (filled to the brim) plus .59Kg of glass

total weight = approximatly 451 Kilogrammes

NOW

on four legs 451Kg / 4 = apprximatly 113Kg per leg

on six legs 451Kg / 6 = approximatly 75 Kg per leg

remembering always that this is based on the tank being filled to the brim

NOW

the tank is never filled to the brim so the weight will be reduced, but the tank will have a gravel base in the bottom of some sort

gravel weighs somewhere under 2 tonnes per cubic metre

it is safe to assume that that the tank is only filled to 2/3 of the total capacity SO no adjustment has to be made for the weight of the "bed" of gravel

SO

it is safe to assume with some safety margin that each of four legs of a tank this size will take 113Kg of load (and 6 legs will each take 75Kg)

THIS ASSUMES YOUR TANK DOES NOT HAVE A WAVE MACHINE, IN WHICH CASE I SUGGEST YOU CONSULT AN ENGINEER

FINALLY
check the mathematics before you use them but it all looks right to me