Hello can some one explain what's going on I ...

I just checked the AN feed chart for "advanced" users and it does say to feed what you've used, but I would disregard that completely. The beginner version only lists 2-3 instead of 10 nutrients and additives 😂 In other words, 7 of them are a waste of money, and in this case are physically harming your plant. What a scam, I'll never use AN after reading that lol. Good luck whatever you do.

If you're convinced it's not because of the nutes simply because another plant has no issues, you aren't understanding that each plant is an individual. Even human twins aren't identical - one can be allergic to bee stings and the other not... With autoflowers, you simply CAN'T feed them that much - even at the height of their strength in flowering... and I will be willing to bet that the second plant soon starts to show you she can't stand it either. But good luck with the CO2... it won't solve your problems, dear heart... especially not the root rot issues you're coming up on (if they haven't started already)... As I said - good luck.

It's root rot my friend. I Highly recommend you make a clean reservoir with fresh nutrients and 5ml of hydrogen peroxide per gallon of water in your reservoir. I hope it's not to late. This usually knocks it out pretty quickly. Hope this helps

It absolutely is the nutrients, listen to @GrowingGrannie. According to your diary, your plants are being fed a solution of 90% water, 10% pure nutrients. I don't use Advanced Nutrients myself, but that sounds incredibly high for any brand. That would be a ridiculously and unnecessarily expensive grow. At that rate, you'd go through a 1L bottle of nutrients every 10L of feed... that's one day's water consumption for me during flower. And AN are already bloody expensive! Lol You need to read the labels on the bottles as I guarantee they do not say "feed every product at 10ml/L all the way through the cycle". Auto's don't need as much photoperiod plants either, so read the bottle to know at what stage to add each nutrient, then half the suggested dosage (or even less). Also, all those nutrients and additives, but you haven't listed any product that clean the reservoir and combat harmful bacteria like root rot? For example; Silver Bullet Roots. Basically, something that contains low levels of hydrogen peroxide. Without it - and especially with this crazy high EC - your plants are prime targets for root issues.

I apologise but I don't think is becouse of the nutes. I have another one nothing wrong with her. I was planing to get CO2 Bag to see if that will fix the problem.. Thanks

Oh buddy - your EC is WAY WAY WAY too high for an autoflower! I've got one going right now (my Creme de la Chem), she's into her 7th week from germination and she's been screaming at me to lower her EC - which sits right now at 0.6 ... normally, an auto at her age would be happy with an EC of 0.8 but she's not happy even at the lower EC... You seem to be throwing as many nutes at her as you can find... Get back to the basics here - she should be getting grow nutes with an EC no higher than 0.6 - you should only be THINKING about adding in the bloom nutes and boosters when she finally gets to flowering... and when she DOES get to flowering, you should cut back on your grow nutes that are nitrogen-heavy and adding a small dose of calmag at the same time. As for your roots, they're looking pretty grim, I must say - but that again is the result of throwing the whole kitchen sink at these ladies. I would add some H2O2 to your reservoir - about 3tsp - that will help clean them up - but I would tell you to change out your entire bucket right now... Into a bucket that's been cleaned with H2O2, add your basic grow nutes at about 1/2 the strength you've been giving plus some root enhancer like RapidStart and 3 tsp of H2O2... and let her settle out. And just a weird question for you - I'm hoping you're keeping at least 1/2" space between the water and the netpot?? That's critical. Good luck...