Thank you all for your posts and thorough advice. I am now pretty convinced that, while it is a nitrogen deficiency, alot may have to do with our extremely cool/cold summer. Even watering only once a week may have been too much. I fertilized today with a 12% N and an iron sulfate supplement for good measure. The temps are heading up to mid 80s (where we are) so things should improve across the board. I'll keep you posted! Thanks again~

Nobody?

New shoots always come out lighter in color than the old growth. They can also show a deficiency like yours, but will turn dark green once they harden off.

Why are you fertilizing every watering ? You are going to have a salt build up doing that to container citrus.

No , Laaz , WHEN I fertilize , and that is every 10-15 days I add the fertilzer and not in every day watering.

Maybe the CHC doesn't keep the fertilizer and on the next watering is washed away?

At the begining the leaves were completely yellow , and now are looking like this. This is maybe too much or too little of something !

What is weird is that the other twig from the tree is more greenish at coloring

Could be genetic. - Millet (548-)

What about CHC retention?

Does he acts like a mineral garden soil or should be fertilized more often ?

Does the water hardiness affects the quality of CHC medium ?

I always water , since they are outside , until the water goes out , maybe this is wrong , meaning that in this way I wash the medium and fertilizer in it?

Meyermike on the other forum told this:

"When individual nutrients are available in excess, it not only unnecessarily contributes to the total volume of solutes in the soil solution, which makes it more difficult for the plant to absorb water and nutrients, it can also create an antagonistic deficiency of other nutrients as toxicity levels block a plant's ability to take them up. E.g., too much Fe (iron) can cause a Mn (manganese) deficiency, with the converse also true, Too much Ca (calcium) can cause a Mg (magnesium) deficiency. Too much P (phosphorous) can cause an insoluble precipitate with Fe and make Fe unavailable. It also interferes with the uptake of several other micro-nutrients. You can see why it is advantageous to supply nutrients in as close to the same ratio in which plants use them and at levels not so high that they interfere with water uptake"


Very interesting

Water hardness can affect any, and every type of medium. Watering a container tree until approximately 10 percent of the water being poured into the top of the container drains out the bottom is the correct method of watering a container, no matter what type of growth medium is used. Doing so flushes out soluble salts, thereby prevents soluble salts from building up to toxic levels. What Meyer Mike wrote is very common knowledge, long known by growers. Because citrus absorb nutrients in a 5-1-3 ratio, it is best to fertilize container citrus trees with a fertilizer as close to a 5-1-3 ratio as possible. This keeps the fertilizer nutrients in balance with the tree's proper ratio. - Millet (547-)

Ok I got it , so by flushing the soil with 10% extra won't wash away the fertilizer but only the build up salts!

Nitrogen and potassium are very water soluble chemicals. They redly dissolve in water and become totally soluble. Therefore, some will flush out with the 10 percent that drains out the bottom. However, it would take repeated watering, in between each application of fertilizer, to totally flush out all of the two nutrients. Really it is not a problem, unless one rarely every applies fertilizer to the container. Note: much, but not all, of what is called soluble salts, and frequently builds up in containers to toxic levels, is fertilizer. - Millet (547-)

Yes , indeed , on those that I left outside and watered on time with plenty of water there is no salts build-up around the pot, so I must conclude that on my problem is a lack of nutrients and not an overdose.

thank's Millet