General Hydroponics MaxiGro, 2.2 lb

Im planning to use it for hydroponic. Do i need to use anything else, like vitamins, minerals etc, or is it enough just to use this products?

Will it harm fish or turtles?

Is the product supposed to be hard as a rock? seems like moisture got in the bag and it’s solid like a rock.

Can I use this for growing outside pepper plants?