aquarium tank weight

[seeandess]

tank size is 48 inches long x 19 inches high x 12 inches depth,can you tell me approximatley the weight of it full of water please?

[theprof]

179 kg

[gen2]

Converting to metric gives a tank size of
120 cm x 47.5 cm x 30 cm
volume = 171000 cubic cm = 171000 ml = 171 litres
1 litre weighs 1 kg
Weight of water in tank = 171 kg (~376 lb)
Add the weight of the tank itself.

[tony1941]

Since you quote the size in inches, I assume you want the answer in pounds. Two old rules come to mind: "A pint of water weighs a pound and a quarter" (which of course means a gallon weighs 10 pounds) and "Six and a quarter gallons make one cubic foot",

Your tank is 4 x 1 x 1.58 in feet which is 6.32 cu ft. that is 6.32 x 6.25 = 39.5 gallons. This weighs 395 pounds or over 28 stones.(not to mention the glass!!)

[seeandess]

Thanks, very much. Bit too heavy for the wife to pick it up then !!

[theprof]

It's actually 179.339 kg which is about 395.36 lb.

These calculations can only be approximate anyway as they assume that the water is at room temperature and the tank is full to the brim.

[brachiopod]

...plus weight of gravel, rocks etc.

Don't try and move a full tank (even if you think you can) - you will only succeed in breaking the glass and having 179 kg of water all over your floor.

[theprof]

gen2:

You're losing quite a bit of water in your calculations as your metric equivalents are only very approximate: 48 inches is 121.92cm, 19 inches is 48.26cm and 12 inches is 30.48cm.

Using the figures seeandess provided:

volume = 48 x 19 x12 inches
= 10944 cubic inches
= 179339.32 cubic centimetres
= 179.33932 litres

As you say, one litre weighs one kilogram
Therefore the total weight is 179.339 kilograms or around 395lb as tony1941 has confirmed.

Now you may think that I'm being pedantic in telling you that you're out by over 8 kilograms in your calculation ( or worse, almost 20 lb). The trouble with this is that it also represents over 8 litres of water.

Let's assume that seeandess was setting up a marine tank for the first time and had asked this question in a different way, ie how many litres of water would the tank hold.

If he had calculated the number of grams of marine salt to add to the tank using your figures, and did not have accurate equipment to measure the resulting salinity, the salinity would be way below what was required and any fish added would die a agonising death.
Sometimes there is no margin for error.

[kempie]

theprof - although accuracy is often essential to an answer, the question does only ask for an approximation.

Surely a 4.65% error qualifies as "approximate".

[heathfield]

You wouldn't want it to be full to the brim anyway.

[gammaray]

here's a tip for anyone with a fish tank full of water (no fish). Never tie a banger to a stone, light it and drop it in the tank. the main problem is that when it goes off the shock wave blows the tank apart and all the water spills out onto the floor!

[gen2]

A reply to theprof,
seeandess asked for "approximately the weight of it" so I feel that my approximations were legitimate. Thanks to kempie for saying so on my behalf.

[Gef]

This is just for theprof. If you want to be pedantic then the answer is 1756 newtons.

[mibn2cweus]

My unsolicited analysis of this thread is as follows:

theprof, gen2�s original answer came in slightly after yours and I doubt that he was aware of or was deliberately refuting your more precise answer. Although his conversion factor for inches to centimeters was a little off (by less than 2%) I give him points for offering the value in appropriate units (pounds). I would like to note that in multiplying these dimensions together the error approached but was still under 5% which is still a reasonable approximation.

Tony1941�s answer of 395 pounds was amazingly accurate considering that I am dumb-founded by how he arrived at it using his �two old rules�. A pint of water weighs closer to one pound than one and one-quarter pounds, (a gallon of water weights ~8.35 pounds, not ten). Also a cubic foot of water is about 7.5 gallons, not 6.25 gallons. Apparently when using these �old rules� in conjunction the result is quite accurate. Great job Tony1941!

brachiopod, Good of you to point out the dire consequences of attempting to move a full tank so eloquently.

theprof, Not everyone appreciates precision when approximate will do, but I find your answers delightfully informative myself. Who can argue with a free education when the alternative, to simply ignore it, is easily available?

As for the rest, kempie, heath field, gamma ray . . . lol, I agree 100%. I see no wrong answers in this thread and it appears that no one is disputing this. I hope we can all be friends and continue to live in peace and the harmony that only different points of view can bring to the music of intellectual inquiry.

The next pint is on me, Cheers!

Gef, those must be some big fig newtons, where can I get some?

[brachiopod]

Cheers, mibn, I'll just have a lemonade, I think. You know how I start ranting inanely late on Friday nights after a few ciders (and Saturday, Sunday, Monday etc.)....

[theprof]

OK people, I'm busy here eating a giant portion of humble pie and I accept unreserverdly that I didn't come across too well.

Kempie: I couldn't agree more that seeandess only asked for an approximate weight and I should have left it at that. By coincidence, I helped set up a marine tank earlier this week and had it drummed into me about how precise the volume calculation has to be to calculate the salt that needs to be added. I was overly influenced by these thoughts when I answered. A 4.65% error is acceptable under any other circumstances

gen2: I can only apologise again.

Gef: You'll note I said that others may have thought I was being pedantic - I did not state I was being so and I was not attempting to do so. In this context, the accuracy I provided would have only been necessary if someone was setting up a marine tank as I said earlier. I had a scenario in mind and selected one of many possible reasons for the question, which turned out to be incorrect . It was a bit like multiple-choice questions really and you and I know how easily one can come unstuck on these. Aren't Newtons great? The trouble with them is that no one I know uses them in a domestic environment - everyone should be able to measure in the other units mentioned.
What other useless units can you think of?


mibn2cweus: I did realise gen2 was not refuting my answer and it was apparent where the calculations were going astray. It was a reasonable answer all the same and I should not have been thinking of that damn marine tank!
I thought tony1941 was brilliant.

I can only apologise to you all again - this round is on me!!

[seeandess]

Well guys, this has been a fab read, informative, thought provoking and has made me realise that maybe I should have paid a little more attention in Maths all those years ago. And thank you, all of you, for you replies. And NO! The drinks are on us, although you might find them a little 'brackish' for your taste!!

Thanks, C&S

[Bert]

mibn.. must be American, since Tony1941 is quite correct. In good ol' Imperial units a pint of water does weigh a pound and a quarter (20 fluid ounces weigh 20 ounces, i.e. 1 lb 4 oz.) and so a gallon of water weighs 10 lbs. Also the prof's conversion of inches to centimetres (note the English spelling) is exactly correct. I inch is defined (now) as 2.54 cm exactly.

[Gef]

Sorry prof I didn't mean to offend. And by the way have you heard of foot-pounds, foot-poundals etc. These were the units used when I was at school.

mibn are you American?

Bert's answer is spot on for UK units. 1 pint is 568 ml (568 g) and 568g divided by 454g (1 pound) is 1.25 lbs.

[helle]

What a load of [edited by AB]

[mibn2cweus]

Dam! I�ve been exposed! No, not by you helle, by Bert & Gef, Yes, mibn2cweus is an American, not by choice but by birth. Next thing I know you�ll all be showing up at my door for that pint I promised you. I wont be here. I�m grabbin� my passport to come over there for one of them Imperial pints. I suspected life had something more to offer and 20% more is down right irresistible. Just goes to show honesty is the best policy, I�ve been missin� out!

helle, Sorry if your feelin� left out. Have yourself a avoirdupois pint of poof puddin� on me.