Hello guys, is anything wrong about this yellowing leaves on seedlings?

No that’s normal if you started out flowering it that young, not getting enough light for greener foliage, but it would get greener as it get older

Drop your ph to 5.8, and as they grow you increase it. Let them develop there roots, I would started them off in a smaller pot to built that root better. Don’t feed them anything, drop that ph and leave them alone.

Well 6.5 PH for grow period is too high my friend, thats the correct PH on flowering where the plant dont need to absorb that much nitrogen for example (there is a whole table on the internet explaining what nutrients are blocked by a too high or too low PH) and the light green yellow part inside the leaves is iron, i had these issues before, there is also lot of information around that on the internet, leaves should turn that color by excess of water, excess of water make the leaves hanging like without energy like it doesnt want to live anymore🤣, in my opinion i keep saying its iron caused by an incorrect PH in your case too high as its on 6.5, but maybe somebody else thinks different, just my opinion from experiences i had previously

hello friend, about fertilization, it's not guano (guano is bat feces, right?). My substrate is basically inert (peat and perlite at a concentration of 85% + 15% humus). And I don't think It would be a Ph problem, because I am using bottled water (Ph 6,5 from the label). Anyways, I am ordering a phmeter to test that I was quite in doubt about whether or not I was iron deficient, but I no longer believe that this is the problem because the seedling got a lot of sun in the morning and the excess water evaporated so the leaves got better (not able tô upload anymore)

Ah disculpa y sobre que pida iniciar fertilizantes, estas usando guano si lo entiendo bien? Sabes por casualidad los micronutrientes disponibles en ese guano? Pero me parecería raro que pida ya fertilizantes, fijate que yo uso un light mix la mayoria de mis cultivos y hasta la semana 3 cosa asi no empiezo a darles, con guano deben de tenwr suficiente comida para sus primeras semanas, quiza al ajustar el PH fijate en micro de advanced nutrition ese tiene todo tipo de micronutrientes, ya que usas guano pues usas micro como complemento en dosis bajas, llevo usando esto hace bastante tiempo y nunca sufro problemas, ni hojas amarillas ni deficiencias de ningun tipo siempre bien verdito, obviamente es un consejo todo depende de la mezcla inicial de guano que mencionas porque quizas ese guano ya tiene todo lo que nesecitas

Hola de nuevo, orgánico o no siempre es aconsejable medir el PH hay medidores en amazon por precios asequibles (en caso de que no tengas) y resolverlo solamente ajustando PH sí y no, te explico, si ahora usas hierro de canna por ejemplo seguiras sufriendo de la deficiencia ya que tu planta no podrá nunca absorber el hierro (y otras substancias) correctamente y va a ser un ciclo sin fin, yo empezaría por tener un buen PH sobre el 5.5 (y en floración 6 - 6,5) y medirla una vez tengas los fertilizantes mezclados, seguramente con solo ajustar PH se resolverá tu problema ya que seguramente en la tierra hay suficiente hierro disponible pero el PH incorrecto esta bloqueand la absorción, si al ajustar el PH vemos que en una semana las hojas nuevas siguen con ese amarillo en la parte de adentro de las hojas seria buscar otra solución (ejemplo canna que vende hierro solo) o algo parecido de tu grow preferido, y sobre el riego bien entonces, depende del clima, donde yo vivo ahora mismo hay bastante humedad y con regarlas por la mañana tengo y mi indoor cada 2 dias pero claro eso depende, nunca se puede decir x candidad por x tiempo porque cada clima cambia asique no hay problema, solo fijate que no se sobre riegen pero si la tierra esta seca y agrietada pues mejor regar 🤣

Ohh, and the soil I m using: sphagnum and perlite (85%) + worm cast (15%)

No, I am not checking soil pH and I thought It was not going to bem necessary since I will use organic nutrition. Regardless to watering, If I don't do It by night the soil Will be cracking really dry. At least on early growth, I don't think would be viable to water 600-700ml early morning because at 4-5h the soil would be like a desert, but I can try it. about the deficiency, only way I could solve it would be correcting the ph? by any chance could this be the plant asking to iniciate the fertilization?

Estas revisando el PH? Parece falta de hierro amigo pero esto puede ser debido a un PH incorrecto ya que bloquea la absorción de nutrientes, en mi opinion no hace falta regar 2 veces al dia, aunque la tierra este seca no quiere decir que tengan sed, dales un buen riego por la mañana temprano cuando el sol se esta poniendo y dejalas asi, el dia siguiente miras si ellas piden agua (normalmente una planta tan pequeña no necesita tanta agua, en interior las riegas cada 3-4 dias)

Is It due to underwatering? High temps? Lack of nutes (i ve not started nutrition yet)? Sunburn maybe?

even so, around 2pm the soil is already quite dry. I've been trying to fix it by increasing the watering over the days. In dead, I've started watering about 100ml day and 100ml night like 4-5 days ago and I ve been incriasing 50-100ml day. Despite that all 9 seedlings has been acquiring yellowish tones mainly in the new leaves that are born.