Let's say I have a typical 10 gallon tank with dimensions 10" x 20" x 12", and it's filled halfway (5" in height) with dry sand for hermit crabs.

If I fill the tank up with water, will the level of sand decrease?

I'm thinking that it doesn't because of this answer -- sand is insoluble. So the water would just fill the gaps of air first. If that's not the case though, what are some things to take in to consideration?

Not quite sure where this question belongs, so if it's in the wrong place, let me know -- or mods, feel free to move it. Thanks!

  • 2
    $\begingroup$ If the submerged sand is vibrated then it will settle more than it would if dry. $\endgroup$
    – MaxW
    May 10, 2017 at 22:49

1 Answer 1


If your sand is packed in a optimal sphere packing, like a hexagonal packing for example,

enter image description here

nothing would happen to the sand level, because it can't be packed more dense.

If the packing of the dry sand wasn't optimal (which it probably isn't 100%), then the water may help settle it through motion and friction and it would lower a bit. In any case it wouldn't lower so much as that you could easily see it with your eyes.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.