Jean wrote:
Hello,
Where can I find the way to calculate the quantity of sand I need?
The "beach" sand takes how much volume?
And how sand weight?
For example, it says on a bag 7Kg.
How much bags I need to buy?
Here's a wonderful little substrate calculator...it works for Flourite,
Eco-Complete, Regular Gravel, and Silica Sand.

http://www.plantedtank.net/substratecalculator.html