If "grainy" means crystals, that can usually be controlled really well with diet. When Oscar had crystals AND an infection, the food change dissolved the crystals in about a week.

HUGS to you and your boy. Remember - if he is happy and eating and playing and purring and pooping and peeing - great stuff!

I don't think you have to change your boxes more often or anything.

Looking forward to hearing he is HOME and the rest of the news!