Dumb question
- Thread starter craig
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Pounds into Gallons: Multiply the specific gravity of the liquid by 8.33* (weight in pounds of 1 gallon of water); then divide the number of pounds by the result, to obtain the volume in gallons.
HAHHHAHA you figure it out
http://www.peteducation.com/category_summary.cfm?cls=0&Cat=1305
HAHHHAHA you figure it out
http://www.peteducation.com/category_summary.cfm?cls=0&Cat=1305
Archimedes' Principle basically states that an object placed in water will displace water equal to its weight. Therefore, 50 lbs of gravel or rock will displace 50 lbs of water. Water weighs 8.33 lbs/gallon, so 50 lbs = 6 gallons of water displaced by gravel or rock, leaving approximately 69 gallons for water (assuming the tank is filled to the top).
icthyophile;664436; said:
I am confused....
Please allow me to babble for a moment, then tell me how wrong I am and why...
Let's take a cube of water 6.1358 inches per side. This should be one gallon, 231 cubic inches and weigh 8.33 pounds.
So far I am with myself ......
Now take that same size cube of gold & place it in the water... 1 gallon of water is displaced, correct?
Now take your 231 cubic inch block of solid gold & weigh it..
The gold weighs in at roughly ... lemme go check .... 160 pounds give or take. but it only displaced 8.33 pounds of water...
Ok, we don't use gold for substrate...
Back to the real question...
Generic stone/gravel varies in specific gravity from about 1500~2500+ kg/cu.m.
Pure water is 1000 kg/cu.m. (salt water 1021 ish)
(gold is 19320 kg/cu.m)
You need to factor the specific gravity into the math....
If we assume an average sg for your rock of 2000 kg/cu.m. ......
Your 50 pounds of "ROCK" will remove 25 pounds of water (3 gal). leaving 72 in the tank, and the net increase of the weight of the filled tank is 25 lbs higher than water alone.
using the base range of 1500~2500 we can safely assume that the 50 pounds of rock will actually displace between 2.25 & 3.75 gallons of water.
The only way to know for sure is to mark the tank in gallons(halves, quarters, eights) , fill it part way.. add the rocks.. check the level,,, now reverse the mass & find the actual specific gravity of your substrate....
.....
I am done confusing myself now...
please set me straight...
as you know I love you all, & won't take offense.
Correct, weight and volume are different. You have density, mass and of coarse if your aquarium was on the moon.......
I think that this question can't really have a strait answer. the weight of the gravel has no baring on the water it displaces displacement depends on the size of the gravel. the size of the gravel is what displaces the water.
then if you go into sand its a whole different story again.
a pound of sand has a different volume size compared to a pound of rocks, to a pound of gravel.
the only way to answer this is to fill whatever tank you got with the substrate. and then measure each amount of water you put into it.
lil stinker is on the money.
then if you go into sand its a whole different story again.
a pound of sand has a different volume size compared to a pound of rocks, to a pound of gravel.
the only way to answer this is to fill whatever tank you got with the substrate. and then measure each amount of water you put into it.
lil stinker is on the money.