75% will be good for correcting that low ph, parks the Herc&Oly in the middle of the rootball, but eventually need to get back to little heavier, to saturate and continue to drive salts and acids deeper in the pot. Plus once in full flower its important to maintain moisture levels in the rootzone because too dry can cause all kinds of issues.......over watering too, its fine line And everyone's grow is a little different.
And don't sweat BK yet, your plants are taking up everything and then some, so until you are ramping to 1600+ feeds and 60 - 90 ml of HERC its kind of a non issue....this is where BK can be your best friend!! Im roughly week 3/4ish now and havnt used BK yet but will prolly start this coming week if numbers allow. I just came off a tea day followed then by a 1500 ppm feed, gonna load it up one more time in 1500's then start introducing BK in feeds as I'm at 45 ml Herc now and will be at 60 ml very soon!! And even though I'm gonna be at 60 ml Herc, I will only introduce BK at 5 ml to start(1/2 strength) .