Help: Mixing 10 gallons of NSW using H2Ocean salt

[GoFish]

Question: 10 gallons of water to _ cups/ounces/lbs etc... of salt?

I've been using Instant Ocean, basic $39 a bucket stuff ($29 when on sale) since starting out. It says on the bucket to use 1/2 cup per 1 gallon of water. 10 gallons = 5 cups of salt. Easy peasy. I fill up the 5 gallon water cooler jugs at home with R.O. so my batches of NSW are done in 5 gallon increments.

Today, bought a bucket of H2Ocean+ to try out. The label says
"Add 1 Kg H2Ocean+ to 25 litres of R.O. water (1 Lb to 3 U.S. Gallons)"

This can surely be figured out with a calculator but I'm jet-lagged
... Anyone?

Thanks in advance!