Living in Florida I maintain my in-ground pool and spa all year long - myself. We have many pool supply stores down here, the most impressive are the mom and pop stores. Leslie's tried to sell me on powdered chlorine years ago - asked about downside - I was told that there were none. I quickly found out that the powder dissipated more quickly than the liquid chlorine - and as I did my research I was told that I would need to drain the pool at least once a year when using powder. That didn't sit well with me since the cost of water down here in Florida isn't exactly cheap. I also found that every time I went to Leslie's they would take my jugs to the back to fill and once in a while you would hear a "Holy crap" back there - indicating that once again I have a hole in my jug thus having to buy another jug. I know chlorine is a corrosive (I was a Haz-Mat cop), but every time inside 30-45 days? Comon!
I'll stick to my baking powder, and muriatic acid along with my wire brush and my Hayward Vacuum - but most importantly I will without a doubt stay with my liquid chlorine!