as you can see in the picture these plants look overwatered, they were watered since first day in this aeroflo 15min on/45min off.. besides the overwater, I did some over nuting as well, some have symptoms on couple of leaves..
first day when I saw the drooping leaves I changed the water and flushed them with clean water for 2 days on the same timer schedule 15/45, but they never changed.. now I have them in this state for over 2 days..
don't know what to do.. continue wasting my time and money waiting for them to come back to normal or start over??
(ps this is my first attempt to grow)

it looks like you could have a salt build up, thats why you add the least amount of nutes first and slowly add more. flush your plants with a bunch of ph balanced (5.5) water. get a ART DNe adjustable recycling timer and adjust time for like 15 secs on 1 min off or even 3 mins off and slowly raise your on and off time to what your plants need. good luck

I have used aeroflo type systems many times over the years and even ran them with no off time at all and never over watered them. I do not think that is your issue here.

Give us some other specifics such as ppm, ph, air movement, exhaust.

I suspect this is a air movement/ph combination thing, just a guess till you give us specifics but one from experience and having seen this same thing before.

I'm gunna hop on RD's bandwagon here - overwatering in an aeroponic system is a very hard thing to do unless you've got some backed up drainage or plugged holes somewhere.

If you are going to go on a timer, i'd recommend your standard 1 min on, 4 mins off fixed timer. These are ideal for cloners and aero systems as I've used them in my store quite a bit.

I'm sure with much larger plants it could be slightly different, but I must say this is the first time i've seen a 15 min on 45 min off cycle proposed with aero. Can't confirm nor deny anything with that type of schedule - but I will admit I'm a bit hesitant on the "45 mins off" part. Seems like a long time to aerate free dangling roots.

i never made daily notes on what was the temperature or other things like pH..

usually they were on 18/6hr under 2x400W lightening, temperature 17-18C for the nighttime, 23-26C for the daytime; pH between 5,5-6 (I have the ph test kit from GHE,so cannot tell exactly..) they had the air extractor on for the 15 min they were fed then off for 45min and so on.., another fan for air movement in the room was always on..
the EC of my tap water is 0.5mS/cm (250ppm), nutes added and made it 1.0mS/cm (500ppm).

the plants were fine for a week or so, after that I rised it to 1.4mS/cm (700ppm) and seen that they didn't like it, on 2 plants the leaves start drooping leaves, and only after a day when all of them had drooped their leaves I changed the water in the system, and flushed them for about 2 days with clean water..

I think you are right, I might fuck up with the pH after i was preparing to start the 12/12 cycle by changing the bulb from MH to HPS for the last couple of days, it gives a more redish spectrum of light in the room and maybe I wasn't adjusting the pH under 6 but it was closer to 5.. dunno what to think but my plants are getting worst every day, their leaves are getting more yellow, it appears they are underfed or something..

I'm so disappointed and hopeless.. I want to throw them away and start over, but what if this will happen again with my second try? I need to find out the mistake I made.. and if this can be fixed or is it too late to save them?

at the moment i have them on 24 hrs lights on, feeding EC 0.7 (0.5 of tap water + 0.2 from nutes) and still getting worst as you can see..

I see some tiger claws in the back left of the Multi plant picture - definitely some ph issues there.

Aeroponics is a dangerous world to dab into if you don't have a digital ph pen brother. That would be my first piece of advice for you.

Them root look like they are gettin to hot..
What is your rez temp???

All of your numbers sound correct to me, hmmm so what is causing this. I think I will take the Dr House approach, he he, nutogrow brought up a idea of the roots being hot, being that they are going 45 min without a nice cool drink at a time and they are under very hot lights, it may be as simple as that. Try changing your cycle to something more like 1 min on 4 min off and ensute that your water temps are 60=64f and you may just see the problems go away.

I dunno about the rez temp coz I cannot mesure it.. I think it is cool enough, if the room temp is at 18-19C then the rez shouldn't be too hot.. I see some mold already on them roots.. it becomes unbelievable for me that they will survive.. is it still possible?

You could try some Hygrozyme. Read up on it and see what ya think.. Your temp should be ok. At least borderline. Is your pump in your rez??? That will help heat the nutes too.