two weeks after germination, yellowish spots appeared on leaves. what the problems should be? fungal infection? over watering? nutrient burn?
Thanks 
Boyuan
@archipilot filling out a support ticket will help! Ill tag some others over to weigh in.
@dbrn32 @Covertgrower @Screwauger @Countryboyjvd1971 @bob31
So many questions, but first, what is the ph?
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THE pertinent question! And what means of determining the ph do you use? @archipilot?
That is a classic ph issue.
COPY/PASTE: This “Support Ticket” into your forum post.
Answer these simple questions the best you can.
If you do not know, or do not use something; Just say so = NA
Strain; Type, Bag seed, or NA
Soil in pots, Hydroponic, or Coco?
System type?
PH of runoff or solution in reservoir?
What is strength of nutrient mix? EC, or TDS
Indoor or Outdoor
Light system, size?
Temps; Day, Night
Humidity; Day, Night
Ventilation system; Yes, No, Size
AC, Humidifier, De-humidifier,
Co2; Yes, No
Add anything else you feel would help us give you a most informed answer. Feel free to elaborate, but short, to the point questions and facts will help us help you smile
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Are you feeding ? If so whats your ppm
What type of medium are you ising or is it a hydro ? @archipilot and welcome to the forum
More info is need a support ticket is best
@MattyBear is in point with what the ph of the water you are using
Also is it well or city
@Myfriendis410 good question and thanks for linking the support tkt
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First guess is calcium deficiency. Looks like you are in hydro? If you can answer the questions in the support ticket the peeps here will have you right as rain in no time.
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Ool, but coming by to check tag. Looks like I’m late lol, carry on gentleman.
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I have a pic here witch looks very much like what’s happing to your plants .Take a look
This is very large but you need to know.
Calcium (Ca) -Macro Nutrient and an Immobile element.
Calcium is another important element that helps the plants cell walls, cell division in making the plants stems, stalks, branches stronger, as well as contributing to root growth, mostly the newer root hairs, Calcium also helps enhancing the uptake of K in the the plants roots. Calcium moves really slow within the plant and tends to concentrate in roots and older growth.
When plants exhibit a Calcium deficiency the younger leaves are the first to show it as well as older leaves. The Leaf tips will die back, the tips may curl, and growth of the plant is stunted. The plant can show a weakness in the stems and branches, as well as a under developed root system that can lead to bacteria problems with roots dieing off. Having slow plant transpiration rates can aggravate the uptake of calcium. Make sure your soil isn’t very acidic, for calcium gets harder to be absorbed through acidic soils, Which leads to having a plant that is deficient in Calcium. The leaf tips, edges and new growth will or may turn a yellow/brown color that happen in spots and often surrounded by a sharp brown outlined edge and then the leaf tips die back. If too much calcium is given at an early stage of growth it can stunt the growth of your plants. Having to much of calcium will also flocculate when a concentrated form is combined with potassium. The parts affected by a calcium deficiency are the roots. Stem or petiole, young or old leaves.
Too much Calcium will lead to other micronutrient deficiencies. Calcium fixation is caused by many types of mediums such as: clay soils, unbuffered coco and humus. The lime tends to bond to these soils very easily. The stems of the plant will not be able to hold the plant up and will exhibit a white brown in between the veins of the leaves when having too much calcium. Also having to much potassium and or nitrogen will cause a calcium lockout.
Problems with Calcium being locked out by PH troubles
Very acidic soils with excessive potassium, dry and or wet soil. Lack of calcium in the soil may cause too acidic soil. This may cause to Mg or Iron deficiency or very slow stunted growth
Soil
Calcium gets locked out of soil growing at ph levels of 2.0- 6.4
Calcium is absorbed best in soil at a ph level of 6.5-9.1 (Wouldn’t recommend having a ph of over 7.0 in soil) anything out of the ranges listed will contribute to a
Calcium Deficiency.
Hydro and Soil less Mediums
Calcium gets locked out of Hydro and Soil less Mediums at ph levels of 2.0- 5.3
Calcium is absorbed best in Hydro and Soil less Mediums at ph levels of 5.4-5.8 (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 a Calcium Deficiency.
Solution to fixing a Calcium deficiency
To fix a calcium deficiency you can treat by foliar feeding with one teaspoon of dolomite lime or Garden lime per quart of water, Or Any Chemical/Organic nutrients that have Calcium in them will fix a Calcium deficiency. (Only mixing at ½ strength when using chemical nutrients or it will cause nutrient burn!)
Or you can take crushed up dolomite lime or garden lime in a gallon of water and water it in the soil. 1 to 2 teaspoons per gallon of water, which will be slow acting. Garden Gypsum, which is medium absorption. Limestone, which is medium absorption, Rock Phosphate and Animal wastes which are both medium/slow absorption. Note: Caution when using gypsum to an already acid soil (pH that is less than 5.5) can have a very bad effect on different types of plants by effecting the absorption of soil aluminum, which is poison to plant roots.
Now if you added to much chemical nutrients and or organics, (which is hard to burn your plants when using organics) you need to flush the soil with plain water. You need to use 2 times as much water as the size of the pot, for example: If you have a 5 gallon pot and need to flush it, you need to use 10 gallons of water to rinse out the soil good enough to get rid of excessive nutrients.
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Beat me to it has Cal def written all over it a Raise in ppm or ph adjustment is in order figure out which when ticket is filled out
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