silica blast?

so on the bottle it says to use it throughout the whole grow...but my friend at the hydro store said to use it solely during flowering...any input will help guys...and thanks in advance.

I use it throughout the grow, but in small amounts (1/4 tsp/gallon), and usually every other week.

I don't use that particular product, but ProTekt from Dyna-Gro. Cost ~$12/qt. Good stuff and a source of K also.

Wet