I have a 75 gallon tank with about an inch of gravel. I am going to salt it for ich but Im not sure how many gallons Im actually left with here.

Help me!!

well the water goes though the gravel ,and you can see it in the gravel
(sorry kinda hard to explain)

Yeah but gravel takes away some gallons because it takes up room.

sorry for not being very helpful

What about doing a water replacement test?
1. Take some gravel and fill a measured container 1 inch deep.
2. Fill the container with water.
3. Empty the water into another container.
4. Clean the gravel out of the measured container.
5. Pour the water from the other container, and measure how many gallons are remaining.
6. Multiply the amount of gravel used in the test by however much is in your tank, and adjust the results accordingly.

I'm no math genius, but i think something along those lines might give you the answer you are looking for!
Hope this helps,
Dana.

Thanks Dana!! I dont know if Ill be able to figure that out though!

Im hoping daryl sees this as shes great with these types of things.

How deep is the tank? U can do this equation:

1/y x 75 = gravel volume

Just replace y with the depth (inches) of your tank

Is the / a divide sign Riz?

And when you say depth do you mean top to bottom or front to back?? (Sorry Im slow).

yep

Yep it a divide sign and it's top to bottom. So if your tank is, say, 16 inches deep then it's 1/16 x 75

Thanks Riz, you are a big help!

Arrgh, I cant get it to come out! My tank is about 18 inches high..

(1 / 18) x 75 = 4.16 gal (I would say 4 gals)

So the gravel takes away only 4 gallons? Thats a lot less than I thought!

hah dont worry fish crazy, i got what you were trying to say ( I thought the same thing )