Both will work, it'll just take longer to dissolve. Like I said I've only used the liquid but I've read on here that's definitely how to use the powdered form. I would really suggest picking up a Taylor test kit, either the K2006 or K2006-C. I got mine from Amazon thru one of the mods links but I don't see the K2006 on Amazon right now, only the K2006-C. Here's the link to the K2006-C. This kit will allow you to test higher CL levels and also test your CYA levels.