yellow spots first week!

It is not a calcium issue.

Soil too hot = slight burning.

Leí su diario y espero que regrese pronto para poder regar, de lo contrario morirá. Las manchas es por falta de riego. Saludos

looks like there's virtualyl no node spacing, so raise light a few inches.. as far as the blemish.. it's tough to know for sure this early. those first 2-3 sets of leaves are often fugly no matter what. as long as it doesn't get worse, you can ignore it. watering should be triggered not a whim. when top 1" dries in soil, irrigate entire volume (a little runoff is fine but a lot of runoff wastes your soils amendments). rinse and repeat. how often you fertilize depends on the concentration that you feed at as well as the charge of nutes in the soil and slowly supplementing more as that is drawn down. trial and error is the only way to learn.. be systematic but when you see problems, review your history of how you ramped up and fertilized and adjust that early process next time.. continue until you find a procedure that works consistently without symptoms arising. The worst thing people do in regard to watering is letting their feelings dictate.. they want to give X gallons or Y liters instead of what is dictated by the soil and it's characteristics. they doon't wait for a proper wet-dry cycle to occur. This promotes deeper roots and more robust root system as well as lowers risk of detrimental pathogens and pests. the trial and error you have to engage in to figure things out is where you use your brain.. Even with that, he plant and its behaviour dictates all choices. never start top-down rationalizations (inductive reasoning) unless devoid of relevant info and all you have is a guess..

looks like there's virtualyl no node spacing, so raise light a few inches.. as far as the blemish.. it's tough to know for sure this early. those first 2-3 sets of leaves are often fugly no matter what. as long as it doesn't get worse, you can ignore it. watering should be triggered not a whim. when top 1" dries in soil, irrigate entire volume (a little runoff is fine but a lot of runoff wastes your soils amendments). rinse and repeat. how often you fertilize depends on the concentration that you feed at as well as the charge of nutes in the soil and slowly supplementing more as that is drawn down. trial and error is the only way to learn.. be systematic but when you see problems, review your history of how you ramped up and fertilized and adjust that early process next time.. continue until you find a procedure that works consistently without symptoms arising. The worst thing people do in regard to watering is letting their feelings dictate.. they want to give X gallons or Y liters instead of what is dictated by the soil and it's characteristics. they doon't wait for a proper wet-dry cycle to occur. This promotes deeper roots and more robust root system as well as lowers risk of detrimental pathogens and pests. the trial and error you have to engage in to figure things out is where you use your brain.. Even with that, he plant and its behaviour dictates all choices. never start top-down rationalizations (inductive reasoning) unless devoid of relevant info and all you have is a guess..

could be an early sign of a calcium deficiency it could probably do with a drink ideally with some quarter strength calcium/magnesium based supplement mixed in you really should be measuring the runoff liquids ph to atleast get an idea of what ph your medium is . if the ph is too high or too low you will have nutritional problems thruout the entire grow. DON'T be tempted to overwater at this early stage as that will only make matters worse and risk damping off of your seedling Good luck mate 👍