I like bud expresses idea...a transplant would sove all your problems if you use quality soil (fox farms oceans forest I has been recommended to me) but if you can't transplant then I would flush those plants heavily with ph correct water (6.2-6.8) 3 -5 x the size of the pot (1 gallon pot....3-5 gallons of water) By the end of your flushing the ph should be the same going in as going out.

Id like to recommend 1/4 strength nute mix at the end but not that 20-20-20 stuff at all so don't unless you have something along the line Stinky recommended.

Is your lighting on 12/12? If not no...you can't tell at this stage if they are male or female. Without that info or how old they are etc.....plus photos of the nodes who knows he or she.

You can use baking soda to raise ph in a pinch and distilled white vinegar to lower it.
DONT use ph adjusters for aquariums....fyi.

Good Luck.