Does salt displace water?

[rockies]

I know that salt should normally be mixed before being added to a tank, but in this case I'm setting up a new tank with nothing in it at all except the hardware. In other words no rock, no sand, no livestock, nothing. I do have the sump, skimmer, etc running perfectly and all the water levels are perfect. If the power goes out the sump backfills to an acceptably safe level.
So, now I want to add salt. I have a total of 170g of water (DT and sump combined) and a bucket of salt that I plan to add. The bucket of salt is about the volume of 5 gallons.
The question is: Should I remove 5g of water before adding the salt to account for the physical displacement of the salt in order to keep the water levels constant? Does the disolving of the salt occur without dispacing any water?
I know I'll figure this out firsthand, but any help before hand will be much appreciated.
TIA
Rockies

 

[bang guy]

Yep.

 

[speg]

There is only one thing that can be put into water without causing water displacement to occur.... know what >it< is? Nothing.
By the way for all you silly people that think those turkey deep friers are dangerous... stop putting the peanut oil to the top of the friggin thing and then adding the turkey.

 

[monalisa]

Originally Posted by Speg
By the way for all you silly people that think those turkey deep friers are dangerous... stop putting the peanut oil to the top of the friggin thing and then adding the turkey.
:notsure:

:thinking:
OK...
Lisa :happyfish

 

[speg]

Originally Posted by MonaLisa
:notsure:

:thinking:
OK...
Lisa :happyfish

Dunno whats with me today... im weird and excited and happy... im usually not any of the three except the weird one. :happyfish

 

[rockies]

Thanks Bang Guy!
Here's what I tried and what happened:
1) First I did a little kitchen experiment with a cup full of water and .25 cup of table salt. Added the salt and the cup of water became ~1.25 cup. :thinking:
2) So I removed 5 gallons of DI water from my system and sat it aside.

3) I added the 5 gallon bucket of Instant Ocean salt (this bucket is specified for 160 gallons). :joy:
4) Watching the water levels in the sump I didn't notice any rise from a back-fill siphon via the return pump. Nor did I notice a rise in the level in the DT itself. Interesting... :notsure:
5) I started the pump and watched the levels in my sump and tank. The DT started to fill, the sump started to drain, but the level in the sump got too low and I had to stop the pump from running dry. :notsure: This caused the tank to back-fill the sump once again.
6) I added back 2.5 gallons of water and the level in the sump returned to where it was originally. :thinking:
7) Turned pump back on and the tank is operating as before. Salt is mixing nicely. I'll check levels in 24 hours or so to fine tune. :joy:

The hypothesis I'm making is that a given volume of salt displaces approximately half that volume of water. My conclusion is that since the salt is a solid and isn't as dense as the water it is entering (there's a lot of air in the bucket of salt) it displaces less.
Rockies

 

[jerthunter]

There are spaces between the water molecules and the sodium ions and chloride ions split about when the salt is added to the water and these ions fill the spaces between the water molecules. From what I understand that is the main reason why adding 5 gal of salt to water won't increase your total volume 5 gallons.