Potassium (K) Mobile Element and Macro Element
Potassium plays a big role as well. Having good amounts of potassium in your plants helps in having sturdy and thick stems, disease-resistance, water respiration, as well aids in photosynthesis. Potassium is also found in the whole plant. It is necessary for all activities having to do with water transportation. Potassium is necessary for all stages of growth, especially important in the development of Buds.
Having to little of Potassium in your plants causes the plants leaves to show retarded growth and show a scorched tip and edges around the leaves. Plants may stretch and your branches can be easily broken or weak. Don’t get this deficiency confused with iron, because it almost acts like iron but to tell the difference in the two is: for potassium the tips of the leaves curl and the edges burn and die. Older leaves may show a red colour and leaves could curl upwards. Dead patches (Necrosis) can happen on the margins of larger fan leaves thus, the leaves will eventually die off and turn brown. The Older leaves will show different patches of colour (mottle) and turn yellow between the veins, following by whole leaves that turn dark yellow and die. The plants overall growth slows down, mostly when they are in vegetative stage. To little amount of potassium also slows the growth of buds during flowering stages. Dark edges will appear around the edges of the leaf when the deficiency is starting to happen. When your Relative humidity is low, you can almost bet your going to soon get a potassium deficiency from your plants perspiration.
Potassium can get poorly absorbed when having too much Calcium or ammonium nitrogen, and maybe cold weather. Having to much sodium (Na) causes potassium to be displaced. SO keep those in mind… Parts affected by a Potassium Deficiency are: older leaves and leaf margins.
When you have too much Potassium in your soil, it can lead to big troubles, like salt damage and acid fixation of the root system, as well as too much potassium can cause a calcium deficiency. Your fan leaves will show like a light to a dark yellow to whitish colour in between the veins. Due to a molecular imbalance, potassium toxicity can cause a reduced uptake and lead to the deficiencies of Mg, and in some cases, Ca. Also leads to the other nutrients to not be absorbed properly leading to lots of other deficiency such as: magnesium, manganese, zinc and iron and can cause problems with calcium as well.
Problems with Potassium being locked out by PH troubles
Soils with excessive Leeching and High ph soils and or water.Soils that are potassium fixated. An excess of kitchen salts (sodium) in the root system/environment.
And once you have a lockout of one mineral its compunded bc then other minerals are being lockedout i think you have a both of these lockouts
Iron (Fe) Micro Nutrient and an Immobile element
Iron is an important component of the plants enzyme and is also important for the transportation of electrons while photosynthesis is happening...
Iron reacts with many of the components of nutrient solutions, which will cause a nutrient lockup to occur, If you add to much Iron without adding enough Phosphorus, you can contribute to a phosphorus deficiency , so watch out how much iron and phosphorus your nutrients have. The Leaves on the plant can turn a pale yellow along the growing shoots, while the veins remain dark green. When you have pH imbalance, it can make iron insoluble. The tissue between the veins becomes pale or white, kind of mimics the magnesium deficiency, but not yellow, iron has the white where the yellow would be on the magnesium deficiency. The deficiency starts with the lower and middle leaves, while the new leaves become completely lacking in chlorophyll, but with little or no necrotic spots. The chlorotic mottling on new leaves starts first near the bases of the leaflets, so the middle of the leaf appears to have a yellow mark. Iron is difficult for plants to absorb and moves really slowly in the plant.
Harder for outdoor plants to absorb when in hot weather. Parts affected by the Iron Deficiency are: Young leaves and Petioles.
To much Iron can cause a problem that looks like a PH imbalance, Brown spotting on the top leaves, mainly fan leaves. Can affect the whole plant. Iron Toxicity is rare for Ph below 5.5.
Problems with Iron being locked out by PH troubles
Over watering, pests nematodes, not enough drainage, like not enough perlite. High ph, Soils with low iron, High Phosphorus, Excess Zinc, manganese or copper.
Soil
Iron gets locked out of soil growing at ph levels of 2.0-3.5
Iron is absorbed best in soil at a ph level of 4.0-6.5 (Wouldn’t recommend having a soil ph of over 7.0 in soil) anything out of the ranges listed will contribute to an Iron Deficiency.
Hydro and Soil less Mediums
Iron gets locked out of Hydro and Soil less Mediums at ph levels of 2.0-3.5
Iron is absorbed best in Hydro and Soil less Mediums at ph levels of 4.0- 6.0 (Wouldn’t recommend having a ph over 6.5 in hydro and soil less mediums.) Best range for hydro and soil less mediums is 5.0 to 6.0. Anything out of the ranges listed will contribute to an iron deficiency.
Solution to fixing a Iron deficiency
Any Chemical/Organic nutrients that have potassium in them will fix a Iron deficiency. (Only mixing at ½ strength when using chemical nutrients, or it will cause nutrient burn!) Foliar feed with chemical fertilizer containing Fe or rusty water can work well. Other supplements that have Iron in them are: Iron chelates, Ferric oxide, Ferrous oxide, Ferrous sulfate, all of these are fast absorption. Greensand, Cottonseed Meal is slow absorption, Garden Manure, which is medium absorption. Manure is most common organic iron source to use.
If you go look in forums informary thread then tips knolwege base you will find this
https://www.autoflower.org/f7/basic-deficiencies-list-11.html should give you everyything you would wanna know about sick plants