Leaf Tips White And Edges Sawtooth Upward

[Hchaz]

I'm new to hydro growing, just entered flowering 2 weeks ago. The edges of leaves from top to bottom of plants curling upward. Sawtooth I believe they call it. The tips of many leaves turning white. During veg I was getting brown spots so I started calmag every other week and that fixed it. It looks like heat stress but it's near bottom of plant also. Could it be potassium def because to much cal mag?

 

[One drop]

Back off on the nutes it's burn what ppm are you running .

 

[Hchaz]

I'm doing dwc and starting with emeralds recommendation of 5ml/gal running around 1200 ppm with a consistent ph of 6.4. Plants are drinking about 1 gal every 2 days so I'm topping it off with straight ro water. My ro is 0012. I read one of your posts where you said to underfeed them. I'm new to hydro and have been upgrading as I go. Next batch will use a rdwc I'm building now so I can monitor and replenish easier. I made the mistake of buying a complete kit setup and have replaced every part of it so far with better quality parts.

 

[One drop]

Run your ppm at 800 to 1000 and see how she fairs mate I wouldn't go over 1000 ppm .

 

[Hchaz]

ok, still getting the burnt tips, leaves curling upward. Root balls big and white, 5.8 ph, room humidity 50-55% temp during light period 75-85 deg, 65-70 during light off. Buds growing decent...more fan leaves are yellowing. I'm using emerald harvest 2 pt and adding calmag every other water change. I start with a 900ppm then every other day refill w straight ro water. When ppm hits around 300-350, I replace with new batch. Maybe I'm just being paranoid and over thinking this. First indoor grow dwc while I build my rdwc system

 

[m8ty]

Found this info for you in another post:

"A good way to judge whether or not, your mix is "too strong" or "too weak" is:

After a fresh nutrient change; Check you ppm. Check again the next day. If your ppm has lowered, then your solution was too weak. Add.5 of the difference in fresh to day old solution and try that.

If your ppm is higher then your solution is too strong. Add water and maintain a lower ppm level"

 

[Hchaz]

I was running 1200-1400 ppm and getting the upward leaf curl and burnt tips, it was suggested by a few that I lower ppm to 600-900. It's def using up nuts quickly.

 

[visajoe1]

I think she looks fine. Its only the tips, and very little yellowing, so she's hardly out of whack. You can dial down the nutes a bit, but you def dont have an emergency, so dont worry. Lastly, EC is what you want to measure by, not ppm. 1.2-2 EC is the common levels run in veg and flower

 

[Seven Trees]

I think she looks fine. Its only the tips, and very little yellowing, so she's hardly out of whack. You can dial down the nutes a bit, but you def dont have an emergency, so dont worry. Lastly, EC is what you want to measure by, not ppm. 1.2-2 EC is the common levels run in veg and flower

PPM is more accurate than EC, simply because the value is expressed in four digits rather than two. Meters which display only EC cannot express minute differences, such as the difference between 1200ppm and 1210ppm. EC is simply a less accurate means of communication and record keeping. If you want precise values, use PPM.

PPM itself is derived from the EC value. They are the exact same measure of salinity. Meters simply read EC and display its value rounded to the nearest tenth or hundreth, while PPM readings convert the true EC value internally to express an accurate PPM. Expression of this is influenced largely be region. North American manufacturers tend to express this value in PPM, while European and Asiatic countries tend to express this value in EC or both.

Further, EC and PPM are not accurate means of evaluation of crop health, nor available nutrients. They do not show relative balance between available nutrients, and therefore act as a misnomer for evaluating plant health and crop performance. Plant health and crop performance is more accurately assessed and predicted using brix refractometry and an Albrecht style interpretation of a base saturation soil test.

EC or PPM only measure the conductivity of specifically salts. Any bond between a metal and a nonmetal is a salt. Many plant available nutrients are not salts. Conversely, many forms of salts cannot be used by plants and will only cause detriment to the rhizosphere through buildup in the cortex, thereby obstructing flow through the endodermis, resulting in a loss of osmotic pressure and slowing of plant sap, nutrient delivery, energy storage, and synthesis of tissue.

This graphic may help in understanding the anatomy and mechanisms I've discussed.

For a more casual and general discussion of this topic, you may be interested in Agronomist Mark Wittman's interview and explanation of some of these points:

 

[Seven Trees]

As your crop transitioned into flower the increased potassium demands were not met. That is very very minor potassium deficiency. Do not augment nutrients at this stage in flower.

In future crops of the same strain in the same environment, consider daily foliar sprays of extremely mild potassium applications throughout the transition period, from flip until pistils emerge. That should alleviate the total potassium demands of your plant, and the minor lack of balance your nutrients are capable of. Do not assume that increasing your PPM will solve this. By increasing the concentration of an unbalanced solution, you are just as likely to cause burn from excess of another mineral. Whether or not the plant can handle higher PPMs depends on genetics and environment. However, your leaves in all photographs are too dark green. This indicates an already very high level of nitrogen. If you are unable to supply individual nutrients, and are using a premixed solution, raising the PPMs will likely result in nitrogen toxicity (the claw).

Further, nitrogen is a difficult nutrient to manage wisely. Increased use increases yields. However, that comes at the expense of a decrease in quality and storage life. Shelf life, flavor and potency will improve with less Nitrogen throughout flower. Yields will be marginally reduced.

 

[Seven Trees]

To make an effective and cheap home made organic potassium foliar spray, learn about Korean Natural Farming; specifically a recipe called FFJ, which stands for Fermented Fruit Juice.

 

[Brotherdorkins]

Too much light! How is your humidity also?