I really would appreciate any advise for the next ...

Ye my gorilla cookies suffered a bit of that I had it at 6.5 though. For me it happened when I give it calmag for the 1st time .she didn't like that . It had already got everything in the soil it needs I just thought I would give it a bit of a treat 🌱

i agree your ph has restricted uptake of certain nutes already mentioned, keeping this in check is paramount or you will never get a good outcome.this is the basics of growing anything..

Nothing to do with the lights, your pH of 5.5 is much too low for soil cultivation and is affecting nutrient availability. In soil, a pH around 6.4 would be much more plant friendly. Your plants also seem to have a magnesium deficiency, but this could also be as a result of the low pH. Next diary, fill in as much information as you can, including what fertilizers you are using, this information is vital for determining solutions to problems.

Hi, looked a bit at your diary my guess would be a big Ph fluctuation during early flowering which they don't like it and got stunted. You can tell it's PH when a healthy plant start to become yellowish all over. Then deficiencies will start to appear because some nutrients cannot absorbed and growth almost comes to a stop. Hope I shed some light on what went wrong. Good luck

Aye pal. If that's your first attempt, I want to say well done for the set up you've got is brilliant. The issue is clearly the light has fried the tops of the plants causing loose buds. Also, you've not put which nutrients you are using. Could be some issues going on there also. With that system you'll be smashing it in no time. But that light especially for autos in that sized tent max power 75% and I'd be cautious still.