Dry acid?!?!

[FirebirdYcamaro]

I just got this new pool to take care of and I have never been in contact with dry acid before. Does SODIUM BISULFATE look like HTH? Their is a whole container full of this stuff that looks like HTH and when tested with small amounts of water reduces the PH level. How would I go about adding this to the pool to lower the ph, this stuff does NOT dissolve in water. thanks!