28 days.....Hmmmm if it aint getting worse don't panic could be simple relocation of nutes within plant due to flowering. It does look like slight overfeeding (same as i get on LSD... no mater how much i drop ec.)
Ph 5.7... adjusted.... you say you bring ph down about 0.5 which would put your nutes before adjusting @ 6.2..... as your using CANNA Aqua .......
read up on Canna aqua..... once nute tank ph set at start....... i set @5.5 as i rises.......... you DO NOT need to adjust again it will always say within 5.2 and 6.2 that is how canna aqua is designed. Even if it hits 6.3 it will lower itself, you DON'T need to add ph up or down after first setting. Too much up or down can cause root issues.
This aint your problem as I don't think you have one, it's just a tip.
I use the full Canna range... have for 16 yrs...can't be beat and I've tried em all. Expensive .... but Quality shows.
I do think big bud or PK should be used on it's own, and not together.... and canna nutes Don't like other additives added other than CANNA products .. this can lock nutes out as they are NOT designed to work together. If you go to the Canna site and sign up you'll find loads iof useful info... FARRRRRRRRRRRRRRR more than any other nute producer.... but they have invested MILLIONS more $$$ into research than any other company.
Good Luck.. looks like your have a nice crop if things go according to plan.
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