Do the leaves look normal like this?

[AgedMaster]

As fertilizer "BIOBIZZ Try-Pack Indoor Starterset" was used and the "Greenception, GCx 4, 120W" as a light source
Sorry for the misleading 150W
This is the link to the instructions for the fertilizer https://www.biobizz.com/wp-content/uploads/2020/01/Nutrient-Schedule-EN-2020.pdf
And actually, i appreciate the "nit-picking" @SmokingWings
As an extra information: the plant is in the 3th week of the flowering phase

What temperature feed do u give your plants u could be feeding to cold

 

[SmokingWings]

I'm still curious about your LED. You said 150w, then you said about 250w. What is the make and model of your LED? LED bulbs will be rated for the amount of power they use, and also rated for the light output "equivalent," meaning as compared to a regular incandescent bulb.

And to add to the confusion is the thing with the wall draw wattage of the LED fixture. Using that "Corn Cob LED" bulb as an example it is rated at 30 Watt. My understanding is that the rating put on the package or the bulb itself is the wattage that the bulb is designed to use at full power. However, many of the people who test the LED lights say that the actual wattage drawn at the wall or actually used is about half of that rating.

From what I have read the reason behind the bulb only using approximately half of the rated wattage is that if the full wattage was allowed the LED bulbs or fixtures could start to burn out in a matter of days to months. So, if they put in the little electronic gizmos and throttle back the wattage the diodes can last years.

Who would want to buy the LED lights if they burned out that quickly. Defeats the advantages of the lights.

 

[013]

Hey FarbFilm, - welcome to 420...!

in order to help you we need more info, can you drop answers for the questions below

What do you mean by watering using the 1/3 or 1/4th rule?
Are you adjusting ph?
To what value are you setting ph?
Do you add nutrients each time you water?
What size are your containers?
How often do you water?
How much volume of water do you give in 1 watering session?
What prompts you to add more water?

 

[bluter]

And to add to the confusion is the thing with the wall draw wattage of the LED fixture. Using that "Corn Cob LED" bulb as an example it is rated at 30 Watt. My understanding is that the rating put on the package or the bulb itself is the wattage that the bulb is designed to use at full power. However, many of the people who test the LED lights say that the actual wattage drawn at the wall or actually used is about half of that rating.

From what I have read the reason behind the bulb only using approximately half of the rated wattage is that if the full wattage was allowed the LED bulbs or fixtures could start to burn out in a matter of days to months. So, if they put in the little electronic gizmos and throttle back the wattage the diodes can last years.

Who would want to buy the LED lights if they burned out that quickly. Defeats the advantages of the lights.

he's got a legit 120w draw light. mfgr claim is replacing 250w hid. it's a bar type light. really only for a single plant. i'd personally go larger even in a 2x2.

 

[BeccaBuds]

at 25C and 85% RH, your temperature is little low and humidity too high. 27C-28C at 50%-60% would be better.

 

[FarbfilmMicha]

Hey, thanks again for the replies, I took a look and read through the Molybdenum deficiency and unfortunately, it describes exactly what is happening with the plants. The leaves are dropping and discoloring like in the pictures. You had the question how cold it is when the light is off. It is 14 ° C and again about the lamp, I do not know if you have looked at it, but just to explain again: It draws 120W from the current, but has a light output of 250W.
Otherwise, I would have a question about how bad it is if the plants are really affected by the molybdenum deficiency and what can be done about it. If it should be too cold, how do you get the box warmer?

 

[SmokingWings]

he's got a legit 120w draw light. mfgr claim is replacing 250w hid. it's a bar type light. really only for a single plant. i'd personally go larger even in a 2x2.

If the "rule" that the minimum of 35 watts per square foot is still valid then the light is just short of meeting that level.

If it should be too cold, how do you get the box warmer?

Add another light.

 

[bluter]

You had the question how cold it is when the light is off. It is 14 ° C

that is too cold. cannabis stalls out at 14c and will not develop. the plant can't warm up enough in the stretch between 14c and your daylight high of 24c.

If it should be too cold, how do you get the box warmer?

extra light could help. i use a heater in my veg room which is too cold otherwise.