Still problem with plants... + pictures

Hi guys.

I post some time ago that I over watered my plants and add at the same time nuts, so my plants got down and so on. One plant died, but 4 plants is fine... 2 days ago I recognize yellow dots on my leaves, check out some sources and find out that it may be calcium deficiency ... I cut off my previous nuts with NPK 13-40-13 and add new very light nuts with NPK 3-6-6 and + calcium... 3 plants still fine after two days but one get some sh*t again. There is the pictures...



These are White Widow plants, week 4 of flowering... I have 250W HPS and 6x23W CFL's...
Temperature is about 25C and humidity ~60%...

What is your opinion? What to do now with this problem... I think I do everything well...

If someone think about some kind of bugs, I check out there is no sh*t like this...

I think maybe some kind of mold or mildew? But I have very good conditions, air ventilation and circulation...

No idea whats wrong

Hey Bro,
Mold or mildew is usually white, when you can't figure out what may be the prob, FLUSH FLUSH FLUSH. Some say well if you got N or P or K defficiency Flushing makes it worse however in my experience at least that eliminates all other doubts. What's your grow medium? if soil then hit them with 6.5-6.8 PH and measure the run off water PH, PH problems beleive it or not are more common than anything. Also again if soil and 4 weeks into flower, have you flushed in the past? if not ur soil ppm might be too high, again flushing can help with that. I know you said u overwatered but letting them getting too dry does that to leaves too(kinda drying around the edges). U wanna do something now or even if plants survive bud quality and weight won't be all that gr8. Best of luck.

It is soil... PH is 6.5 in soil but I have no idea what PH is in the water...
I don't flush them before.
But I kind of scared to flush maybe I will over water them again and will lost my whole crop... :/

Well that's why you wait till top inch or 2 of soil is dried out. When you water, you have to make sure you get some water out anyways, flushing is just getting a lot more water in, a lot more water out. Usually rule of thumb is water twice the size of your pot for flushing. Unless u don't have good enough drainage, flushing is NOT over watering.

BTW 2 most common insects/mildews don't look like that. As mentioned, powdery mildew is pretty obviuos and White and powdery, and the SPIDER MITES(most common MJ plant insects) don't leave marks like that, just yellow dots on the leaves and they're somewhat easy to see, even sometims without microscope.

So if I have 12L pot with about 8L soil, then I need to flush with 16L of water? This is what I understand from you! And how often do I need flush them?

I'de suggest it looks more like nute burn than anything else. What nutes are you feeding it and whats the NPK amounts?

That's correct, flushing is good to be done every 4-6 weeks depending the amount of nutes u use and the ppm of the water going into ur soil. If you use distilled or RO water then u need less flushing, same with nutes.