I would recommend that this cat get off of ANY and ALL grocery foods, and the ROYAL CANIN. Coming from a cat only clinic, we find that any foods besides Science Diet do a huge detrement to cats urine...especially one that has been blocked before. He should really be eating a canned food diet, probably science diet c/d, and if he wont eat the canned he needs to be on the c/d dry. Also, DISTILLED water. Filtered and reverse osmosis are not the same. Distilled is 100% pure water and will help keep the crystals and infection from reinvading his bladder and urinary tract. You will find that even though science diets foods are a little more expensive, you need to generally feed less of them and your medical expenses will be greatly reduced because they just dont have the problems with it. Your cost will actually be less when you sit to figure it out. Good luck!