Substrate - Dusty?

[Pirarucu]

You need to add water or it won't stick together.

[MrBosc]

Originally Posted by Pirarucu

You need to add water or it won't stick together.

OK, I was actually wondering whether I should do that as I was putting it in because the top soil bag said "expand up to 25l when water is added". In that case is there a particular amount of water I should be aiming to put in there?