Green Gelato Noobie

Over the week I've started to notice that the tips of the leafs are getting yellowish now compared to last weeks light green spots. My runoff EC is about 0.200 less than my intake. my run off PH is also a bit high at 7.5ph and my intake PH is around 6.2. I will try this week to lower the PH and feed it 5.5-6 maybe that will do something to help here. I also thought maybe a flush of just ph controlled water would help. Will see. Any ones input is welcome. :) The ladies are definitely growing. They are about 14-15 cm now. The one which appeared smaller last week over passed the other. Will keep posted. 01/12/2022 - flushed the ladies with 2L of water each at a PH of 5.5. The run off is still high (PH7.5) not sure how to lower it. It just doesn't want too. 01/12/2022 - I can see discoloration just on the left one, the right is not as affected i think. 02/12/2022 - found the problem, my PH meter needed to calibrated. It was not showing the right PH.