I've seen that happen to Grow Big after just 6 months. I would dump it. Of course mine had been opened and used regularly and not uncommon for me to dump it at the first sign of solid matter in the bottom.

I believe (though no expert) that a lot of salt would accumulate in the crystals.
grey1223 Reviewed by grey1223 on . Is my Fox Farm still good? I have some "grow big". Been sitting for a couple years and some of it has crystalized. Is it still good? Rating: 5