how much ounce or gram in an IO cup ?

I do mine by weight 1.5 pounds of IO to 5 gallons water. you will need 19.5 pounds of IO salt.

Bill

[catshanon]

Thanks to everyone for their help. Finally I can get my tank up and running.

[Marlin65]

I took a container that was about the right size for the volume of water I wanted and threw that salt filled up to the top into the bin. Then filled it with water until I hit the right salinity. Put a mark on the bin and now I just fill the bin with water to the line and throw the salt in from the container and it is the same always.
makes changing the water a bit smoother.