not sure leaf problem plz help

here are pics. 29 days in flower growing under avanced led ds 200. temps never over 80 with lights on. using advanced nutes. was only feeding 3ml of base instead of 4mls trying not to burn. at first sign i flushed with several gallons cause i thought it was nute burn but its been several days and its getting worse. is it phos. or mg i use only ro water.

Phosphorus.

looks like a def, flushing with gallons of water at the first sign of what u thought was nute burn wasnt the best idea, at first sign of what you think is nute burn you just skip a couple feedings and give just water, under Heavy Salt build up is when a flush is required.

what u actually did was rid ur plant of the little nutes it did have..

wait till dry soils and give it back 4ml nutes.

thanks for your help it is well appreciated