Potassium def or nute burn, or something else?

Hi all, I have an auto plant under T5 in flowering stage. Actually have a growjournal, but I have been told I will not get any reply to my problem there. So I try this trhead, maybe someone can help me to the right direction.
The lady is in soil coco and perlit. The light is 30cm from the top. The temp is between 25-30C RH is 21-35 day and 50-60 at night. A few days ago I noticed the problem, since I feed with tap water, no nute at all, and I also flushed the medium 2 days ago. This is my first auto plant and cannot decide what is going on. Anyone here can help me with that?

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Csak it looks like fingertipping - over feeding.

The leaves will never recover but you can stop the spread. Try cutting back on your nutes or water next time without nutes.

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Hobbes said:

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Csak it looks like fingertipping - over feeding.

The leaves will never recover but you can stop the spread. Try cutting back on your nutes or water next time without nutes.

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Click to expand...

overfeeding you mean too much nute, yes? well I have already stoped feeding her, just only tap water. and she looks like the issue is not spreading, so hopefully the flush I did after feeding tap water it will help. I usually water her every 3-4 days. What do you reckon when shall I start feed her with blooming nute safely? like nute, tapwater, nute system?

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Your plants are ready for Nutes, just not as hot a solution as you've been giving them.

It's hard to get a good estimate of how much Nutes to give, the manufacturers always print directions that say to use too much - and you get fingertipping.

Does your soil have any Nutes in it?

If not, give them 1/4 strength and build up as the plants mature.

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Hobbes said:

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Your plants are ready for Nutes, just not as hot a solution as you've been giving them.

It's hard to get a good estimate of how much Nutes to give, the manufacturers always print directions that say to use too much - and you get fingertipping.

Does your soil have any Nutes in it?

If not, give them 1/4 strength and build up as the plants mature.

.

Click to expand...

I feed her as per the direction said, but that is too much for this strain. Anyway I ll reduce the amount at the next coming up watering time.
I think the soil empty by now 'cause after veg stage she was showing signs that she is hungry.