need advice

Your problem is definitely overwatering and not enough light combined.

Soil looks very poor quality.......this is the issue I believe. If they are autos, starting again would probably be the best idea. If they are photoperiod plants, repotting them into fresh, quality soil (the best you can afford) might save them. P.S. - always fill your pots right up to the top, this way the plants sit up high and get the most light, and the more soil, the more roots and the more roots, the more plant. I suggest you go to the Mandala Seeds website and read their "grow guides", it is full of great information and might give you some valuable pointers. Good luck!

You're overwatering. Let the soil dry out some between waterings.

All the leaves are tightly packed on stem -- clear sign of light stunting. Need to wait a bit longer for those seedlings to develop before blasting with light. Would need to clear that up before properly assessing any potential nutrient-related issues.. if any.. could be coinciding due to too much light and nothing wrong at all.. so fix 1, then re-assess (assumes none take a distinct nosedive in meantime*). common sense applies*