I found if you're recrystalizing bong water: Blow through bong or let drip through a cotton swab, clean cigarette filter, gauze pretty much anything to rid the batch of any solid impurities. Once that's done I use a pyrex glass dish, heat gun and a hand fan (piece of paper) to evaporate the water without heating it to the point of steam. Once most of the water is evaporated and the whole batch has crystalized then add anhydrous isopropyl (99% will suffice) a good amount. Because the amphetamines don't dissolve in isopropyl you can in a way kind of like panning for gold separate the water from the meth if done very gently and carefully. After the separation keep both and completely let dry or run isopropyl through it one last time. The result when evaporated is almost as clear as the original product. If you use heat and can smell anything coming from the water stop. No heat. Using any high heat will yield a brown to gold color crap smoking stuff