johnny... what you using for nutes?  I'd say one of a few poss problems... either nute lockout via ph ( check your soil or runoff from your soil)
or possibly a potassium / magnesium or even both deficiency...
	
	
		
		
			Potassium: Leaves have a papery appearance; dead areas along the edges of leaves; growth is stunted...
 
Magnesium: Lower leaves turn yellow along the tips and margin and between the veins; the lower leaves wilt...
		
		
	 
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.
 
 
Soil
 
Potassium gets locked out of soil growing at ph levels of 4.0-5.5
Potassium is absorbed best in soil at a ph level of 6.0-9.5. (Wouldn’t  recommend having a ph of over 7.0 in soil) anything out of the ranges  listed will contribute to a Potassium deficiency.
 
 
Hydro and Soil less Mediums
 
Potassium gets locked out of Hydro and Soil less Mediums at ph levels of 4.0-4.5, 6.0-6.5.
Potassium is absorbed best in Hydro and Soil less Mediums at ph levels  of 4.7-5.3, 6.7-8.5. (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  potassium deficiency.
 
 
Solution to fixing a Potassium deficiency
Any Chemical/Organic nutrients that have potassium in them will fix a  potassium deficiency. Again Peters All Purpose plant food 20-20-20, will  cure the potassium deficiency , Miracle grow Tomato plant food, Miracle  grow All purpose plant food.( Only mixing at ½ strength when using  chemical nutrients, or it will cause nutrient burn!) Some other  supplements of potassium are: Wood ashes, which are fast absorption,  Kelp Meal, which is medium absorption, Greensand, which is slow  absorption, granite dust, which is slow absorption. Sulfate of Potash,  Sulfate of Potash Magnesia, Muriate of Potash, which are medium  absorption. FOXFARM GROW BIG HYDROPONIC CONCENTRATE, which is fast  absorption. (

GB can bring your ph down as well) Earth Juice Meta-K,  which is fast acting. (Can bring down your ph as well) Leaves will never  recover, but the plant will show recovery after about 4 to 5 days when  using a fast acting nutrient.
 
 
Note: Wood Ashes, can make your ph go up a bit, so please monitor your ph when using it.
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.
 
Picture 1 and 2 shows a Potassium deficiency
 
 
		
		
	
	
 
 
 Magnesium (Mg) - Micronutrient and Mobile Element
 
Magnesium helps supports healthy veins while keeping a healthy leaf  production and its structure. Magnesium is significant for  chlorophyll-production and enzyme break downs. Magnesium which must be  present in relatively large quantities for the plant to survive, but yet  not to much to where it will cause the plant to show a toxicity.
 
Magnesium is one of the easiest deficiencies to tell… the green veins  along with the yellowness of the entire surrounding leave is a dead  giveaway, but sometimes that’s not always the case here. In case you  have one of those where it doesn’t show the green veins, sometimes leaf  tips and edges may discolour and curl upward. The growing tips can turn  lime green when the deficiency progresses to the top of the plant. The  edges will feel like dry and crispy and usually affects the lower leaves  in younger plants, then will affect the middle to upper half when it  gets older, but It can also happen on older leaves as well. The  deficiency will start at the tip then will take over the entire outer  left and right sides of the leaves. The inner part will be yellow and or  brownish in colour, followed by leaves falling without withering. The  tips can also twist and turn as well as curving upwards as if you curl  your tongues.
 
Excessive levels of magnesium in your plants will exhibit a buildup of  toxic salts that will kill the leaves and lock out other nutrients like  Calcium (Ca). Mg can get locked out by having too much Calcium, Chlorine  or ammonium in your soil/water.
One of the worst problems a person can have is a magnesium def caused by  a ph lockout. By giving it more magnesium to cure the problem when you  are thinking you are doing good, but actually you are doing more harm  then good. When the plants can’t take in a nutrient because of the ph  being off for that element, the plant will not absorb it but it will be  in the soil… therefore causing a buildup. A buildup will be noticed by  the outer parts of the plant becoming whitish and or a yellowish color.  The tips and part way in on the inner leaves will die and feel like  glass. Parts affected by Magnesium deficiency are: space between the  veins (Interveinal) of older leaves; may begin around interior perimeter  of leaf.
 
 
Problems with Magnesium being locked out by PH troubles
 
Light Acid Soils, soils with excessive potassium, calcium and or phosphorus
 
 
Soil
 
Magnesium gets locked out of soil growing at ph levels of 2.0-6.4
Magnesium 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 Magnesium deficiency.
 
 
Hydro and Soil less Mediums
 
Magnesium gets locked out of Hydro and Soil less Mediums at ph levels of 2.0-5.7
Magnesium is absorbed best in Hydro and Soil less Mediums at ph levels of 5.8-9.1
(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 Magnesium  deficiency.
 
 
Solution to fixing a Magnesium deficiency
Any Chemical/Organic nutrients that have Magnesium in them will fix a  Magnesium deficiency. (Only mixing at ½ strength when using chemical  nutrients or it will cause nutrient burn!)
Other nutrients that have magnesium in them are: Epsom salts, which is  fast absorption. Dolomite lime and or garden lime (same thing just  called different) which is slow absorption. Sulfate of Potash, Magnesia  which is medium absorption. Worm Castings, which is slow absorption.  Crabshell which is slow absorption. Earth Juice Mircoblast, which is  fast acting. (a must buy!! Has lots of 2ndary nutrients).
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.
 
Picture one shows a mid grade magnesium deficiency.
 
(Pictures courtesy of -43)
 
 
 

 
 
 
 
 
 
 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 colour 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.
 
Pictures 1-2 shows calcium deficiencies. First one shows late, 2nd one shows early development.
 
 
 
ref:  
https://www.autoflower.org/f7/basic-deficiencies-list-11.html