Why is King eds instant ocean so much cheaper?

[Aquattro]

Here is what IO should be.

IO - All based on using 41.6 grams per liter and yields 35 ppt to mirror natural sea water.

pH 8.0 to 8.3
alkalinity 3.5 to 4.5 mEq/l
calcium 370 to 420 ppm (avg is right at 400 and mirrors NSW)
mag is 1250 to 1375 ppm
non detectible is phosphate, nitrate, ammonia and nitrite