If I've got stuff in a bowl of citric acid I add boiling water now and again. I also get rid of the rust debris. I got a load of very cheap citric acid powder from a fishing store on ebay so always worth checking those as well as the food/bath bomb suppliers. Used in bait apparently. I do think Bilt Hamber Deox C is a bit better but not worth the huge price uplift over the food grade stuff you can find quite cheaply.