Best food with low magnesium/ash/phosphorus

I currently have one cat with FLUTD and he will be on a prescription diet for the rest of his life (better safe than sorry, IMHO). I have another male cat who will be eating a separate diet, as I don't want to put him on the RX diet for fear of pre-disposing him to calcium oxalate crystals.

Is there a quality low magnesium/ash/phosphorus/carbohydrate diet available commercially that you would recommend for a healthy adult? Out of the better foods made by Natura (California Natural, Innova) or Wellness, which is the best one for optimal urinary pH? Does anyone have any experience with the Fromm Family Classic formulation or Wysong's?

I feed Royal Canin special 33 magnesium is .08%. Innova and Natura were to high in magnesium for my cats.

Royal canin and Nutro both make foods that have been tested for UTI health.... I will look thru my research again but I do think only some wet from the makers you name qualify////

Hi Sharky,

Sure, I would appreciate it if you'd look at your research again. Before Pico's FLUTD incident, I was feeding both of the boys Nutro Indoor Complete Care Weight Management. I'm thinking of changing Romeo (the healthy one) over to another food with lower magnesium levels, but if Nutro is one of the foods with reasonable levels, then I'll keep him on it.

Nutros Natural choice is in the okay range but the Nutro max is certified for UTI health....