Spider mites?

Iron deficiency? I’m giving NPK only (currently 15-3-15 time release, and occasional ammonia sulfate) , as I can’t find trace elements minus 46% alkaline lime. It’s all bundled together here. I’m thinking to risk adding a bit of this lime to all my potted citrus just for the elements.

Spider mites and/or manganese deficiency. No iron chlorosis. Take a magnifying glass at the leaves to look for mites and spray with something containing manganese. Spraying for fungal protection with mancozeb usually gets rid of both manganese and zinc deficiency. (All disclaimers for using chemical potentially detrimental to one's health apply).

As Nik wrote, it is possibly a manganese deficiency. However, a manganese deficiency usually shows a greater green border to the sides of the veins, then your tree is showing. You can apply manganese either to the soil or as a foliar spray, or you can do nothing and as the leaves mature they normally will take care of a manganese deficiency on their own. Deficient manganese in a new citrus flush is extremely common.

I'd say mites, they are microscopic

Ok thanks guys. I’ll see what I can do.