Hello buzzkillz, your girls are looking great 💪
To answer your question.
There are different stages of the plant lifecycle so there are also different optimal ph numers that come with it.
First of all in early veg you want to aim at 5.9 or 6.0 not higher.
When your ferther in veg 5.8 is the optimal ph.
Then you have week 1, 2 and 3 of flower between 5.8 and 5.7
Week 4, 5, and 6 you can also keep between 5.8 and 5.6
And the last weeks you can keep it between 5.7 and 5.6.
Last week of week and a half flushing time and then you should be fine.
Hope this was an helpfull answer my friend.
Keep on growing. Peace 👍