Years ago, my Max had these crystals. The food acidified his urine and it was never an issue again. However, the food was also very rich and he ended up diabetic around 9 years old. Everything was able to be managed with food and meds. He was a happy and mostly healthy cat.
Ah, yes. I got a water fountain that filtered and recirculated the water for my cats. That greatly increased the amount of water they drank. It was more than 1.5L per week for both. That helps with this greatly as well.