Virus seldom hits all plants.
Not calcium deficiency. That would kill new leaves.
Suspect the regular doses of trace elements is excessive.
What rate does the package of 5-5-5 say to use? And how much are you adding every week?

Another question for you: Why are the plants indoors?

Hi, thanks for the response.
I'll take it one by one:

Virus seldom hits all plants.
Those are only 3 of my 18, only that look kinda could-be-ill, others are just fine

Not calcium deficiency. That would kill new leaves.
What do you mean? For example this guy seems to have similar problem

Suspect the regular doses of trace elements is excessive.
Aight, I will cut back the ferts...also, I found somewhere it could be a water PH problem, since I did not test my water yet, that could be the case (will buy a tester asap)

What rate does the package of 5-5-5 say to use? And how much are you adding every week?
They say 15ml to 4litres of water and feed once in 2 weeks, I am giving them small doses (same concentration) once a week.

Why are the plants indoors?
That was only for the photos, they are normally outside on my windows (I live in a flat). However, some of the bigger plants tend to struggle with direct sunlight (windows are faced to east, so the sun is shining on them ~7am-12am), tilt drastically and seems to have little sunburns, but when they're on the window inside of the room, they seem fine. I also put the one looking the worst away from the others, inside, since I still dunno if it isn't a virus or something.

Thanks again, I bought some Mg and Ca, so will feed it a little with this (can't do any harm, right?) I am also increasingly more suspecting it could be aphids, I noticed some tiny little black dots, so will get an magnifying glass and have a look.

The plants are fine and healthy, you're perilously close to giving them too much love though.

Water thoroughly, but sparingly and consistently, and allow for some dry time between waterings. Sounds complicated but eventually you'll get the knack for it.

The plant with yellow leaves is either suffering from too much water, inconsistent watering, or low oxygen in the root zone (tightly packed soil with no perlite). There's a small chance it could be something else, like low nitrogen for instance, but i highly doubt it.

Back off on the ferts, and only feed Magnesium and Calcium very sparingly as you can throw off the nutrient balance, or raise the PH too high.

Your plants need more sun, not less. Introduce them to direct outdoor sun slowly. Only 30 minutes on the first day, 45 minutes the second day, 90 minutes the third day, then pull them into the shade afterwards. Most modern windows will filter out certain rays that plants need.

Thanx guys...I will try to overreact less :)

One last thing, isn't it a leaf spot? Can someone check {{gwi:1187558}} if it isn't the leaf spot? It seems to be getting a bit worse on the leaf...

Very unlikely, what you have in that picture is harmless in my experience.

Bacterial leaf spot often starts as a small circle, about the size of the number "0" on your keyboard. As the spot ages it gets a brown color fringed with yellow.

Here is a link that might be useful: example pics

Thanks guys, I am happy to hear that :)