I have mixed raw powders into the old t-gel, & it always required heating. The new stuff will dissolve a lot more, but may still need a liitle heating. Boil a small pot of water & let it cool a few minutes. Then put the bottles in there for 5 min or so. The gel will get more viscous when hot so it's much easier to shake & mix the powder in. You may need to shake/heat a few times to get it all in if you are going for max capacity. Make sure you vent the bottles by turning the pump, but dont take the tops off. I had an uncapped bottle expand while in hot water, then tip over into the water. I lost a little into the water & burned the crap out of my hand.