DWC OG seedlings problems

Hello growers,
just looking for help with my OG babies. I am trying DWC again after 15 years I was doing it for last time. And it seems that I can´t get it right. They are in a 4 liters bucket with the air pump. I got another one just in a little greenhouse and it does great. But these 3 in DWC are not looking great. See attached photos. Using RO water, CalMag and Terra Aquatica G-B-M. TDS around 400 ppm. PH around 5,8. Thank you very much for your help.

do you have a humidifier in there and what light you got them under?

Thanks for your answer. Well I got it under zip bags, each one under a different zip bag. They are like 2-3 weeks old, from seeds being put to germinate. Light was 12W TLED LUXROOTING, but last week they are under CFL 125W like 75 cm away, cos I needed that TLED for clones.