Does anyone know how to figure displacement ?

[newfishliny]

example: I have a 90 gal tank ; and put in 100lbs
of rock what actual amount of water do I have ?
Part 2
is it the amount of water in the tank or the volume of space
that makes for a better environment?

 

[azonic]

Can't really determine it for sure...I dont think so anyway....every single rock is different in porosity and density..... so I dont think you can accurately determine it...but this is just what i am thinking.

 

[almarktool]

as Azonic said u are not going to come up with a calculator for that one i put in 250lbs of Lr and it only took up 20-25 galls of water i would have thought more but i measured it out,
in regards to 2nd question the answer is both , more water makes for less drastic changes in the enviroment in regards to water parameters, and at the same time space is important as well depending on which type of fish u would like to keep as they all have different swimming caracteristics
Mark

 

[broomer5]

Yeah - has to do with exactly what Azonic said.
Each rock is different.
If you really want to know - there are two ways that I can think of to determine the displacement. Neither one is too fun - but will work.
1) Place all the rock in the tank - fill it up - pull out the rock - measure the water drop. No fun.
2) Take a 5 gallon bucket half full of saltwater. Before you add each rock to the tank - first place it in the bucket and measure the water rise in inches. Determine the volume of water each rock displaced in the bucket one at a time, or several at time would work better - then write it down.
When your done doing this with all the rock - add up your numbers and you'll have a pretty good idea of the displaced water in gallons. Still no fun.
Other than that - it's pretty much a guess.

 

[azonic]

Just out of curiousity....why do you want to know the displacement of water in your tank?

 

[newfishliny]

azonic, they way I see it the more water the
better quality of water> besides that I am building
along side of my custom stand a upright 50 gal sump.
its made out of commercial plactic used in factories. also I am
boxing it in with 3/4 ply wood and a birch wood veneer.
more is better(I hope)
your hood looks good

 

[jasonw]

Fing out the weight of one gallon of sea water, it will be a little over 8 pounds. then divide the weight of rock be that and it will give you an approximate displacement.

 

[dburr]

Azonic;
Another reason to know how much water you have is for dosing puposes. For instance, I have 100 gal tank, but not 100 gallons of water. I have more like 75- 80 gallons. If I medicate or try to adjust my water paramiters I would use 80 gallons not 100 gallons when dosing by recommended dosage.
HTH

 

[jester]

Frehs water is 8 lbs per gallon. Saltwater at a .023 saline level is just a hair ove 9 lbs depending on tempature.