Hi, I thought I'd give you an update on Storm. He had crystals in late December and has now been on Royal Canin Urinary S/O formula for about 3 months now. He just had another urinalysis taken and his results are excellent. He doesn't have any more crystals, no signs of bacteria, and his PH level is also normal. I'm so happy to hear this. Hopefully he'll remain a happy and healthy cat for many many more years to come. I'm now feeding this food to all of my furkids so I hope to keep them healthy too.