how much water is really in your tank????

[tygerfifteen]

okay,
I thought that if 1 gallon of water is 10 lbs the my 65 is 650 lbs.
So if my Live rock is 110 lbs and I put it in my tank my tank then has 540 lbs of water in it??
But what do we take in consideration?, the volume of the rock or the density?I mean if I took a Metal brick the size of one of my liverock but weighed 50 lbs heavier would the same amount of water come out??
Would I have to figure out each individual volume for every rock I put in my tank ?
How much weight is really in my tank?
Sorry I suck at math and was never good at it I must of failed like 5 times in highschoo l(lol) so I need a little help in figuring out how many gallons are in my tank and how heavy it is. I want to t
take that in consideration when I'll calculating the inches of fish per gallon, water turnover rate, and watts per gallon(which I don't follow)
thankx

 

[hookedonreefs]

You can't use the general rule you stated. Just bacause you had 65 gal.s in your tank and added 110lbs. of LR, that does not mean you took out 11 gal.s. You have to calculate the water displacement of each rock. I know not easy. You would also have to calculate the displacement due to you substrate.
It's much easier to fill an empty tank up say 1/3 of the way. Keep track of how many gal.s you put in. then add your sand and rock. If the water is going to spill over keep track of how much you lose. (I would siphon it into a bucket. Once rock and sand are added top off you tank with water and now you have the total water in your tank.
This is the method I'm using. It's taking a long time, but this is certainly a "patience required" hobby. Let me know if that works for you, or if anyone else has a better idea.
Good luck!

 

[elan]

Try this nifty calculator:
Go to the following website.
http://www.garf.org/
On the left side, click calculator, then tank water volume.
You enter the tank dimensions, sand weight, and rock weight, and it estimates the volume of water... Not sure how accurate it is since every rock has a different density, but i am pretty sure its within reason for your calculations.