Rock\Sand Displacement.

[ObsessiveProgression]

Speaking in EXTREMELY general terms, about how much NON POROUS rock would it take to displace about 100 gallons of water?

Also, Assuming I decide to go with a DSB, how much water would a 1ft x 1ft x 6 inch section of sand bed actually displace?

Im sure this is just algebra, but I havent had to actually think since high school, so I have no idea how to figure it out.

If Im asking questions like these, can you tell Im almost ready to to actually set up my 350?

[tdwyatt]

It will depend on the snd you're usinmg.
Best to actually measure the displacement. get a large open container that will hold two rothree gallons, then pour in 1 gallon EXACTLY of water. Mark the side of the container so that you will be able to tell what the level in the continer is for 1 gallon of volume. Place the container in a pan that will hold more than 1 gallon (just in cse you overflow the original container), then add sand to the container 1 cup at a time until the container that hoods the water has almost dougled its volume. Remove the water from the container 1 scoop at a time until you've measured back down to the original 1 gallon line. Record how much you have romoved, and compair that to how much sand you added. You can either determin how many grams (or Kg) you have per unit of water, or what volume of sand you have per unit water.

Either way will work for you, calculate how much a cup of sand wieghs and calculate your conversion to how many cups of sand you add4ed per how many cups of water it took to return the waterlevel back to 1 gal.

Easy math. Tap water should be ok, although there should be a small correction factor for SW and FW: if you want to be really accurate, then used full strength ( 35 PPT ) seawater.

[ObsessiveProgression]

Thats too easy. I want this to be hard, complicated and take days of careful study. I want to have to factor in lunar tides and the position of the sun.

put water in a bucket, then measure the sand displacement? nah.... its too easy.... it could NEVER work.