calcified seaweed (Lithothamnium calcareum) indications for use

I have this material and I would like to use it to buffer the soil pH in outdoor.

The lithothamnium I bought is composed of: 85% calcium carbonate and 15% magnesium.

I wanted to have an indication of the quantity to be used in grams / liters. The instructions on the box report 3kg/100sqm for improve the structure and the pH of acid soils.
According to these values ​​for a 50x50 cm wide hole 7.5 grams of litotamnium will be necessary.
I would like to have your opinion ... and it is possible to have a more precise indication in grams / liter

thank you and sorry for the mistakes in writing

can nobody tell me something?

I found a recipe for organic soil that recommends 230ml/100 liters, plus or minus 230 grams... on the net I have found recipes that recommend 125g/square meter... I just need to have a rough indication... thank you and sorry my bad english