For various EC and pH, try HERE.
As for the second part of your question, that's a bit more difficult as it does not sound like you're running a recirculating system.
Generally you start with a known pH and EC nutrient. after its run through the system a day or two, you check the EC and pH again. If both are the same, the plant is using all the nutrients fairly equally. if the EC is higher or lower, your plants are using more or less water than fertilizer repectively. if the pH fluctuates, it means they are using more of some components than others. In general, if the pH increases, you're using more Nitrogen. If the pH decreases, you're using more phosporus.
In your case, since you're not recirculating the nutrient, you'll have to establish a base line of the nutrient coming out the bottom of the plant pots then test again and base your observations on the base line reading.

Thank you grizzman
now i understand how to check the EC and pH again

but i couldn't find my plants on that list.
i need to know EC range for
Brugmansia
Dahlia
Carnation
Morning glory
gaillardia
Petunia
Zinnia
Coleus
Kale
Amaryllis
Narcissus
Celosia
Himalayan balsam
datura

u helped alot, Thank you

Go here and choose from the list below.

http://www.gthydro.com/plantguide.html

I have said this earlier and can only repeat it once more: these tables are nice to look at but rather worthless. If I'd be gentle I'd say "They may give you an idea", but that wouldn't be correct either. Best uptake of nutrients in Hydroponics simply is between PH 5.8 and 6.2 for almost any plant. In most cases it's difficult enough to set and maintain the PH in this range, although nutrients are calculated to end up around this range. No need to set such "special" PH for most plants, except they actually need a DISTINCT high or low PH to grow.

Although for the nutrient concentration it's a bit different, these charts may give you an idea, but they may also give you a wrong idea. I haven't taken any data from these "internet charts" as the aren't coherent and some even ridiculously high. There's no reference where they provide from, if they are based on any scientific or empirical research or else. I've encountered them at some point too as many did, but actually never used any of the data, neither PH nor ppm rates! These charts for various plants are lacking the most important: the recommended or ideal NPK proportions, which actually is the most important part: In fact it's the other way round, the content in NPK,Mg,Ca,S etc, will in fact determine the EC or ppm reading of any decent formula that is SPECIFIC for some plant. Hence, how can one tell or use any "given" concentration if completely ignoring the composition?!

@grizzman,
What you describe about changing PH and EC isn't actually wrong - but in practice it works a bit differently. If you start your seedlings for instance, they do not pull any nutrients and there will be no change in a day or two at all (not even in 3 or 4), concerning EC nor PH -except from PH and EC that settles because of acid nutrients and base (buffer) of tap water. Hence, for seedlings and for the beginning - you much better off when simply using reliable recommendations. You can still monitor, watch and learn.

With maturing plants, data has to be monitored over 1 week at least to show notable and conclusive changes. Those always depend on and are relative to reservoir size and plant maturity. There is a general role: if your PH climbs slightly (or notably) and your EC drops (continuously and by clear tendency) you're set fine. If your EC climbs, (the PH rather drops) the concentration of the nutrient is too high. Too low concentration may theoretically induce very slightly falling EC and slightly climbing PH, but you'll actually observe stagnating of growth or light chlorosis instead. In most cases, toping off (accordingly) will correct both, EC as well as PH, assuming you were having a acceptable PH without use of PH up/down - which is ideal and to aim for anyway. Stable PH mostly depends on good water quality and adequate nutrients.

Important 1: the actual nutrient concentration really influences (lowers) your PH in the first place. Means that your nutrient concentration determines the actual PH in the first place, without any use of PH down/up. Here you can slightly correct your PH through the nutrient concentration to begin with. It's better to have a 0.2 higher EC and .2 lower PH value (as in PH 6.0 instead of 6.2 and 2.0 mS/cm instead of 1.8). Plants will not really care about 0.2 plus EC but will appreciate the lower PH.

Important 2: EC reading is rather INACCURATE, due to imprecision of most instruments and actual relativity to PH. Reading errors of 0.2-0.4 always need to be considered.

"the content in NPK,Mg,Ca,S etc, will in fact determine the EC or ppm reading of any decent formula that is SPECIFIC for some plant. Hence, how can one tell or use any "given" concentration if completely ignoring the composition?!"

that is exactly what i was thinking about!
that is why now im searching about the perfect npk ratio used for diff growth stages for each specific plant and i have a feeling that i wouldn't learn except by experimenting anyway..but atleast i gotta be close to the desired needs for the plants.
i will keep the pH like u said
thanks for ur detailed answer

Hi tiphereth,

It makes (no) sense doesn't it ;-)
Personal researches and tests are fine, I'm doing those since I am into hydroponics. Unfortunately it's not always conclusive and not productive at all (figure of speech). It takes time and you need to be dedicated.

One hint here: do not focus too much on growing stages (as in vegetative flowering or fruiting). I believe this is quite another myth of so many.
Some time ago a quite popular nutrient manufacturer did certified chromatic analyses of "hemp" plants (different strains) in different stages, - in fact vegetative and blooming stage.
The results brought things down to earth quite a bit. In fact all strains did have more N and P content during blooming stage. The proportion didn't even change notably. As for P, which is the biggest myth ever - not even the content was extremely low, but it didn't even change with blooming stage. I believe that the relation of Nitrogen to Potassium doesn't vary much during stages with many plant species. The more soft tissue a plant has and the quicker it grows to maturity, the more Nitrogen it needs compared to K. And the stronger and more complex the tissue (as in stems, stalks, leafstalk, texture, multiple petiole etc.) a plant needs to build up, the more Potassium is required. About Phosphorus needs and uptake during "stages" I am sure it doesn't alter, - simply because phosphorus dissolves very slowly in soil and so the actual content and the resulting availability is always low. Plants have adopted their actual needs of P to this shortage and can't even use any more.

Actual needs and uptake are related to plant size, even if some people give nearly the same rate during all growing sizes and stages and pretend that it is the way it has to be. But Lettuce for instance only takes up VERY little Nitrogen during the first weeks. The needs and uptake rate of Nitrogen is as exponential as the growing rate of lettuce - this is a simple fact.

Such a mess you can't edit posts here!
Please correct this sentence "In fact all strains did have more N and P content during blooming stage."

-> to "In fact all strains did have more N and K content during blooming stage."

yeah don't worry, i knew u meant that :D
Thanks alot lucas
u r a pro ;)