OH and here is a guide that might help out i got this almost a yr ago i forgot where i got it from so sorry i cant give them credit but if u did it let me know dont want to steal your credit
Nitrogen
Nitrogen is a key element in the production of Amino Acids;
Amino acids are the building blocks of various proteins.
Also many plant functions depend on Nitrogen to work, such functions as the production of Chlorophyll, DNA and RNA (Genetic materials), and the production of many enzymes, that help control and regulate growth, need nitrogen to work.
Nitrogen is a very mobile element in the plant.
Plants suffering a nitrogen deficiency show a distinct pattern in the yellowing of the leaves,
A nitrogen deficency does look like over watering and the same can be said of over watering, that in its early stages over watering does look a lot like a Nitrogen deficiency
This yellowing starts on the lower, older leaves and progresses up the plant, leaving the top parts of the plant, the growing shoots and top leaves green.
The leaves have a washed out appearance as the green coloring in the leaf fades and is then replaced by a yellow color.
Feeding with a high N fert will bring the plant back to normal growth.
With deficiencies too, foliar feeding is an excellent to feed the plant deficient nutrients.
The main thing to look for with a nitrogen deficiency is that the large fan leaves will turn pale green, then have yellow patches, first.
The green leaf color fades to a uniform yellow over entire leaf.
Phosphorous
Phosphorous is used by the plant to catch the energy of the light as it is assimilated into molecules called Adenosine-tri-phosphate, or ATP. This substance is necessary for the plant's basic pysiological processes;
such as root growth, flowering, respiration, and vegetative growth.
Phosphorous deficiencies are marked by purple stems, leaf stems and leaf veins.
Plants with a phosphorus deficiency are stunted in growth.
Keep in mind, however, that with some strains of cannibis purple leaf stems and leaf veins are a natural feature of the plant.
As you can see from the photo there is a yellowing of the leaves as well, and general loss of vigor in the plant.
Leaves will also tend to be smaller and dark green, and may or may not include necrotic patches.
Flowers will be small and under developed as will the roots.
the plant will be stunted and lack vigor
On the leaf it is the veins, edges and dead tips where it shows plainly
Potassium
Potassium aids in the process of photosynthesis, nutrient uptake, respiration, and, along with silicon, is necessary for the plant to form sturdy stems and general disease resistance.
Potassium deficiencies are identified by necrosis on the
margins of larger fan leaves.
Necrotic patches can be seen on the other leaves also.
Leaves will turn yellow, then brown and die off.
The plants that show signs of a Potassium deficiency will be the tallest plants in the garden.
Feeding with a good nutrient, high in potassium will bring the plant back to normal health.
or better still a foliar spray of quarter strength nutrient.
You can also use wood ashes and water them into your soil to fix this.
Seaweed is also an organic nutrient high in potassium.
You'll need to replace your soil's holding capacity of Potassium, and have a surplus before it will become available to the roots again.
Secondary Nutrients
Magnesium
Chlorophyll has the same structure as Hemoglobin, except that it has a magnesium atom in place of the Iron atom. Chlorophyll is importand in photosynthesis; that is how the plant produces sugars.
A magnesium deficient plant is identified by intervenial chlorosis(that is, between the veins, which remain a green color), and necrosis. The problems starts at the bottom of the plants and progresses to the top of the plant. The tips of the leaves die and then usually curl upwards
Treating with an Epsom salts mix will bring the plant back to health again.
Sulphur
Sulphur is an important element in the plants production of amino acids and proteins, and is needed for normal plant respiration and the metabolism of sugars and other substances.
Sulfur deficiencies are marked by a yellowing that starts at the top of the plant, and then progresses down the plant; this includes also the veins of the leaves.
Treat the same as a Mg deficiency with Epsom salts.
Calcium
Calcium is an important co-enzyme in the production of fatty acids, cell membranes, and is necessary for normal mitosis/cell division.
A Calcium deficiency will stunt the plant, and its growth will slow right down.
Fortunately, calcium deficencies are rare.
Trace Elements
The six trace elements of Boron, Copper, Iron, Manganese, Molybdenum, and Zinc are not required in large quantities, but are important for various plant processes.
Boron
It isa rare occurrence and is marked by small grey or necrotic patches on the growing shoots which eventually die.
Fixing this is done easily by using a foliar spray containing Boric Acid.
Copper
A copper deficiency is commonly mistaken for an over fertilization, but what marks it is y the growing tips, which die off first, and crispy leaves. The new shoots will die from the tips and margins first, often going brown or white before they die.
A foliar feeding with a commercial fungicide containing Copper (ie. Copper Sulphate) will clear it up, but the damaged leaves will not recover.
Iron
An Iron deficiency will disguise a Magnesium deficiency.
It is the newer growth that will display the intervenial chlorosis which differentiates it from a Magnesium deficiency.
Notice how the top of the plant is showing intervenial chlorosis and the lower part is unaffected.
Manganese
A Manganese deficiency exhibits a general chlorosis, followed by yellow patches and necrotic leaf tissue between the veins of the larger fan leaves.
Molybdenum
A Molybdenum deficiency is marked by yellowing necrotic leaves from the tips inward, with necrotic sections present from the tips inward.
It occurs in the middle of the plant.
It will, however, spread to the rest of the plant if not stopped, and will eventually kill the plant.
Zinc
A Zinc deficient plant has wispy new growth with twisted leaflets at 90°.
Intervenial chlorosis will be present at the top of the plant, and this is very often confused with an Iron deficiency.
See how in this picture the older grown leaves are unaffected.
Other persistent problems
pH
Improper pH can cause an abundance of problems which can be taken for deficiencies.
A pH imbalance may also be the cause of the deficiencies in the first place. pH in soil is best in the range of 6 up to 7.5.
In a Hydroponic system the ph should be in the range of 5.5-6.2.
Over Fertilization
This is a very common problem is often mixed up and with other problems.
Over watering looks like this:
Droopy leaves and lower leaf yellowing are indications of over watering.
Notice how the green color of the leaves is replace with a yellow to white color, this is often mistaken for a nitrogen deficiency;
To much Nitrogen
Notice the claw leaf: this is indicative of too much nitrogen.
and lastly,
radiant Heat
