ph to high and yellow leaves help

ok im in the 2nd week of flowering with 2 females. the ph is almost at 8 even though the water i use is at 5.5 so how can i get that down?

also I've just noticed that the very tips of the TOP leaves are just showing a bit of yellow (im trying to catch it early). they are in the canna terra soil (has nutes) they get waterd when they need it and have been fed once with canna flores about 4days ago

please help i dont want to lose any more plants (3 were male from fem seeds i know i got duped)

hm, i think you double posted, i commented on the other one =) good luck