First grow - yellow curly leaves

[Champagne]

Howdy! Three weeks ago i began my very first grow. All went well until last week when i noticed that my plants are under some sort of stress.

Essentially, the leaves are curling upwards (heat stress i think) and the tips are yellowing. With the exception of one plant, the others have not grown at all over the last week.

I've added some photos in the hope that some of the more experienced growers out there can help me out.

Some more details about my setup:

Medium: coco coir
Food: Flora Duo A (200 ppm), Flora Duo B (100 ppm), CalMag (80 ppm) fed once a week at 5.8 pH
Light: 600W HPS dimmed to 50%, 32" away from plant
Runoff: ~6.6 pH

Any help is greatly appreciated.

Champagne

 

[PurpleDragon]

I think this may be over fertilization because of the curling of leaves and brown spots on some of the tips and fringes of the leaves. I think you caught it early enough.

The over fertilization section in https://www.icmag.com/ic/showthread.php?t=231387 says: "Soil should be flushed with lots of water, Use 3 gallons of water per one gallon of soil. Flush very thoroughly, after plant recovers usually after a week, you can resume using nutrients after a week or a week 1/2. When you flush your soil, you flush everything out, a lot of nutrients go with it, including the soil nutrients."

You may wish to look through the pictures also. It'll be easier for you to recognize similarities since you can see you plant up close and in person.

 

[mango420]

Do not follow the advice that purple said! That is for soil not coco! But he was right on the too much ferts. When u grow seeds and there this small they should be getting tap water, if you have low ppm tap water like 50ppm and under you should give nutes to up to about 200ppm. 400 is way too high for seedlings. Do not start flushing your medium, instead just start giving them water for the next few weeks. You also should not be watering to runoff when your plants are this small. 100ml at a time is about all you need.

 

[Champagne]

Do not follow the advice that purple said! That is for soil not coco! But he was right on the too much ferts. When u grow seeds and there this small they should be getting tap water, if you have low ppm tap water like 50ppm and under you should give nutes to up to about 200ppm. 400 is way too high for seedlings. Do not start flushing your medium, instead just start giving them water for the next few weeks. You also should not be watering to runoff when your plants are this small. 100ml at a time is about all you need.

Thanks for your insight. My tap water is ~400ppm and after the nutes it ends up around 800ppm.

I'll stick to plain tap water at 5.8 pH for the next few weeks and see how that goes.

Also how often should i water them if i go with just 100ml?

Cheers!

 

[Manastasis]

Water them as they need. Theres a fine line between watering seedlings and drowning seedlings. Not soggy. Not dry. They do look a lil bit cooked from hot light. Whatever feed you are growing with give them half strength untill they bust out mature leaf growth. Maybe go a lil bit lower with your ph, like closer to a 6 on your runoff. If you are using tap water make sure you are allowing it to dechlorinate first! The bleach in most tap water can hurt your girls. Hope they take off!

 

[fonzee]

Water twice a day with an EC of 0.5-0.7 mS. Find your ppm to EC conversion ratio on google as it changes between producers.

What are your light on and off temps and humidity?
What do you use for venting?
Did you flush your coco well before using it?