Problem i've never seen before, can't figure it out (with PICS)

Plants started from Babies, up to date they are 7 weeks old. No heavy ferts (400 ppm when the problem started), may be irrelevant. Room is well ventilated (Temp 25C Day / 18C Night) with 2 1000w lights 24" above the plants, Sativa strand, growing in Soil with a ph of 6.5. The problem started right around the first fertilizing, the 3 leaves in one of the pics are the daily stages of the problem until they die and fall off. Please if you have seen this before or have any suggestions it would be greatly appreciated.
Thanks!

what type of fertilizer are you using ? if it started when you first gave it to them then i would say it is something to do with what you are giving them . what kind of water are you giving them would be my next question . if it is plane city tap water i would have it tested .you can take a sample to you local pool supply store or tropical fish supply store to to have it tested . rite now the first thing i would do is give it a good flush with some clean store bought water. i also recommend about 3 parts water to 1 part dirt for a flush.

I don't know why folks always recommend a flush. If it is a deficiency, which is looks like, then you are flushing whatever nutrients there are left in the soil, and the problem can only get worse if you don't give it nutrients back.
https://www.rollitup.org/view.php?pg=faq&cmd=article&id=37

Rudiger said:

I don't know why folks always recommend a flush. If it is a deficiency, which is looks like, then you are flushing whatever nutrients there are left in the soil, and the problem can only get worse if you don't give it nutrients back.
https://www.rollitup.org/view.php?pg=faq&cmd=article&id=37

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Not trying to flame you Rudiger but how does no problems untill after adding nutes = a nute deficiency?

no worries.
They are 7 weeks old. Plants need a good amount of nutrients as they get older. I highly doubt he just started giving them nutes. Well, I am an ass, and for some reason after re-reading it, I missed that half sentence the first time that says it started after giving 1st nutes. Why on earth would you wait 7 weeks to begin nutes?

Sorry I had left out that I started nutes on the 5th week. This is driving me crazy, i've never had this problem before.

http://www.weed-weeds.com/growing-marijuana19.html here is a link thats pretty useful for checking out your deffiency or plant problems, i had something simmilar to that happen and i cured it by adding 10 ml of microblast/gal along with my regular GH 3 part solution i also added 2 more drops of ph down, sometimes you can cure problems just by messing with the ph just a bit

Thanks to all your help and suggestions, the Problem has been resolved I cant thank you enough for the prompt responces
Cheers

what was the solution if you dont mind me asking? Its good for all to learn

Jeffdogg said:

what was the solution if you dont mind me asking? Its good for all to learn

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The PH was completely off due to my PPM/PH Meter's electrode being shotty. Make sure that you clean your electrode with it's special cleaning solution one every 3 weeks (do not reuse cleaner) and to make sure that when you arent using it that the electrode is stored in it's storing solution. Ever since I got a new electrode and have 100% readings, they have done a complete turn around and are Thriving now Thanks again for all the help and I hope this info can help others!