Haha we had the same experiences as youngsters then mate
Maybe I'm still not out of my party days at 46 years old!
Now, I am as stubborn as a mule, and it took me a long time to accept this, but........... forget PPFD etc with that many watts of cobs and autos. In my opinion, you can do MUCH MORE harm to plants, yield, etc if cobs are too low, instead of too high. If your cobs are less than 1 metre away from plants you will have enough light IMO. For AUTOS. I know it goes against everything we "understand" as humans, but I honestly believe this is true with cobs and autos. Don't bother with lenses, keep cobs up high (higher than you think) and leave them there. I think cobs are PERFECT for fairly high level global lighting. Thats what they were designed for I believe? Its because they have phenomenal reach / penetration. The opposite to traditional lighting.
What colour temperature are you cobs mate? 3500k? You have to be careful at seedling stage as there is quite a bit of red in anything 3500k or less. This can def cause stretch in seedlings. I have stretched loads of plants with 3500k cobs. So I now use a T5 6700k light for first couple of weeks. Then under 3500k cobs. The first two weeks under 6700k seems to set the plants to grow a certain way, opposite to if I start them under 3500k cobs.
How do you water them when they are like 0-3 weeks old mate? I think over watering at that stage also has a critical effect on plant size due to root ball size.
From what I have read, PH Perfect nutes can only do so much. I used to use them and assume they would be able to buffer everything I threw in the mix. But remember you are throwing in a lot of additives so it is totally possible that the nutes can no longer keep within the optimal range any longer?
Thanks for realising I just wanna help a fellow gardener mate! I am not an arse, and I have learned a lot from my own mistakes!! Often done more than once!
You know I actually think that NOT keeping a record and NOT having a strict regime is a good way to learn. I did a "blind" grow with no PH, no EC measurement, no temperature or RH etc. I learned soooo much as my only choice was to watch the plants and learn what their reaction to what I do means!
When I say I learned a lot, I can only say I now know more than I did before, thats all.
Keep up the awesome growing dude, you have some lovely plants that are making amazing buds for you to smoke