I was just browsing the web and I came across a few other company that sell chemical for lab purposes and they have potassium nitrate and potassium sulphate at a cheaper price. Would this be any different than those one that is sold by aquaessentials? Some people that I know claimed that they use fertiliser for terrestial plants for aquarium plants. mostly muriate of potash(KCL) or sulphate of potash(K2SO4). Has anyone uses these compound in their tank? Is there any effect of these compound on invertebrates or fishes?