Why are the tips yellow

more than one thing causes that, so you'll have to let it progress to better diagnose if you don't have familiarity with your formula/methods.

Yeah ph I'd kinda important I only use a liquid type test kit as the pens do my head in calibration every other day is a joke so get yourself 1 of those I use vitalink and it's cheap.. other than that it's hard to say but the plant is telling me she just wants water next few feeds and observe... Hope this helps and good luck..

Can you add what soil you're using to your diary? I see you added big bloom on day 11, depending on the medium you're using you may not need to feed for 4-6 weeks. The soil could already have nutrients in it and the additional nutrients you added could of gave them a little nute burn. Says your light is at 20", not a bad height. What intensity do you have it set at though? High intensity can cause leaves to start yellowing. Seedlings and plants in veg don't need a ton of light, around 24" and 30%-40% power will be plenty until flower. Being how young your plants are right now, I would keep light intensity around 30% and if the plant starts stretching, raise intensity.

Hi ich denke das es noch nichts schlimmes ist. Ich würde Aufjedenfall calmag dazugeben entweder als dünger oder als spray ein so genannter blattdünger. Ich denke nicht das es zu stark an dem ph wert liegt wenn du mit Trinkwasser aus dem Laden gießt l.

Looks like ph issue. Let plant establish himself, sometimes it goes away . All bought water usually have ph between 6.5 to 7.0. That is still healthy range. Try adding calmag. But not organic version like BioBizz or so, those organic takes time to be ready for plant to absorb.