help me calculate my water volume

[baby1-]

no sump ,all hob filters and skimmer ,i have a 55 gallon tank48"x18"x12" 50lbs.sand,120 lbs live rock. how much water volume do i have?

[davewbush]

I would say that the rock and sand would displace about 5 to 6 gallons of water. The messurments of the tank are the outside demensions, not the inside, so you loose a little volume there. I would guess 3 gal or so. Skimmer holds a little water. Mabe a gal on the high side. I would say you have between 40 and 45 gallons of actual water in your tank.

I have a 180 gal tank, with overflows, 75 gal tank as sump with baffels, 15 gal refugium, 250 pounds of live rock, 200 pounds of sand. When every thing is turned off my sump is full to the top. This looks like 270 gallons but when I filled up my tank I used 5 gallon jugs to what it realy held and total system is 195 gallons and the tank itself hold 143 gallons. My glass is 1/2 thick. The difference between gallons in a 72x24x24 and 71x23x24 is a lot. And we don't fill are tanks all the way up to the top.

[zachfishman]

This is a good tool:

Aquarium System Volume Calculator (http://reef.diesyst.com/volcalc/volcalc.html)