.. I can only say that the soil is a cellmax universal soil mix (little bit strong for auto's, so I don't need to feed for the first 5 week) and the ph is 6.5. I don't know this information sorry.. I don't know how to do it sincerely
Yeah if you haven't fertilized then the soil you're using might be a little hot. It's definitely not a big issue yet. Nitrogen will be less available if you decrease the pH of your water, even if using plain water. Try to feed it around 5.5 instead for a week or two.
Your plant looks pretty good and should eventually adjust to the soil as it grows larger. I usually use Promix, which gives you pretty much total control over what you are feeding and supplementing, but some growers prefer the pre-loaded mixes. Different strains react differently to the different mediums, so results can vary unless you grow only one strain. The leaf clawing is pretty minor and not a good indicator of nutrient issues yet, but when the clawing shows up, it is much more severe than what you are seeing currently. Just keep it going and I wouldn't feed it anything for a month or so... sometimes the nutrients are time released and flushing won't remove any excesses.
Classic overwatering symptom is drooping with swelling between the leaf veins. Heres a group of seedlings, which one is overwatered? Checked my log and i miscalculated yesterday, it never dried to even close to the original 110 grams. Dohhhhhh! Good news is that its taking 10g water/day so a dry week will help it recover.