Problematic YELLOWING of leaves. Mayday!

Hi guys, i'm here in regards to yellowing tips of the leaves that occurs to ALL of my marijuana plants. I have seen the photo charts regarding different types of canna plant problems, yet i'm unable to diagnose it correctly. Leaves starts to yellow, and new lower leaves are shrinking and not growing in a proper leaf bloom. I'm confused on what should i do with my situation... I will be grateful and much in debt to anyone who can shed some light to my problems.

pH Information:
Soil pH 7.2 <-- I know that this is high, i've been trying many times to lower the pH .. including Battery acid (sulphur) to pH down for aquariums and Distilled vinegar ... the pH just comes back to this number....

The setup:
1x 400w HPS (2 unit coming up soon.)
Premium Compost (w/ worm castings) mixed Perlites
Reverse Osmosis distilled water w/ pH 7.0
Air conditioning with temp not more < 32deg Celcius (89.6 Fah)






Fertilizer that I use (from Indonesia).. these are the best available with macro & micro supplements:




Sick plant (close ups)

you have a case of nute burn. flush all your soils foor about a week and restart with half the nutes you are using. use the top leaves that come out over the next week as a referance point to the yellowing. if they are not yellowing anymore then you have a nute problem as of right now. slowly start adding your nutes again but use only half the dosage that your using now.

the thing is.... i'm already using half of what is advised on the fertilizer label it says 5 grams per 2 litres of water.. and i'm only using 2.5grams per 2 litres.. i've also tried flushing.... continuously .. for 3 days..... no results... and i've transplanted some of of the plants to a bigger pot (and changed its soil to a the new mix) .. these babies i have not given them any nutrients whatsoever yet... its been over 5 days yet im still seeing same thing... any other wordly advise ?

Maybe it has something to do with the soil you're using. It's bought from the store? Anyway if I were you I'd stop the feeding and use only plain water for a while. Good luck!