Help 20days yellow leaf

Anyone can help me identify the problem?
both are 23days from germination. havent yet fed them with nutrition, been watering every 3 to 4days.

What are ur temps, and 23 days form germination...... have u checked ur roots? maybe root bound. Also sartfeeding them nutes go 1/4 of the strenght recomended and try give em Cal Mag also 1/4 of the strenght to start with and give that once a week. keep ph at 6.8 - 6.9 .

How far ur light(s) from plants?


-Jugz

What soil are you in? Looks like they could use some nitrogen rich food. Could be lack of light too but id say feeding issue.

Feed

Using 2 CFL of 23W. Distance between light and plant is aprox 5cm to 8cm range. Humidity 40 to 50%. Temp is is 27celcius.
If light is an Issue, I will change to 2 * 6W LED light bulb. Ahhhh Don't know what is happening but seems Nitrogen deficiency. not sure. but Will start to feed them today.

Thank you again, for advices. So far I could only find Fish emulsion 5-1-1 NPK. I will start feeding them with half dose which was recommended. and adjust PH with Lemon juice. Do I need to add lemon juice every week? people saids PH goes up after few days.

They's hungry. pH every time you water/feed. Not that important when watering unless your tap water is high pH. Definitely every time you feed though.

Save the lemon juice for lemonade. Dont worry about your pH if your growing in soil unless you have reaaaaallllyyy shitty soil like straight peat moss or clay then you dont have to worry about it. Fish emulsion is good if you have a live soil with beneficial microbes and so on. If your soil is dead then the fish emulsion is useless as it needs to be broken down by the microbes first before the plant can utilize the nutrition from it.

Like everyone else said. Feed them baby's.