I picked up some Walgreens Epsom Salt in a 6 lb. bag for $3. The bag has a turquoise color and has the words Magnesium Sulfate written on on the front. On the back, it states Saline Laxative for Internal Usage and Soaking Solution for External Usage. Also, there's instructions for using it as fertilizer on terrestrial plants. My question is, would it be ok for aquarium usage?

