Hi all

I have been lurking around here for a little bit now.
I have recently ventured into live plant keeping.
Have decided to make a homemade co2 reactor.
The question I have is this. "I went to the grocery
store near me {actually an oversized bodega} and
they have only  envelopes of "active dry yeast". I'm 
guessing that this is not regular yeast? 
It says on the back "1 pkg. active dry yeast(1/4oz.} = 
= 1 pkg. cake fresh yeast {0.6oz.}, 1 pkg. of active dry 
yeast measures about 2 1/4 tsp"
Can I use this stuff? I am no chemist. Or should I just
toss it? And get reg. yeast?? 
any and all responses will be greatly appreciated.