"Hi everyone, I'm a newbie grower and after a cycle with a 400W HPS, I upgraded to a Sanlight EVO 5 100 LED because of the high temperature from the HPS (it reached 32°C). So I started a new cycle with 4 plants in a 100x100x200cm grow tent. I have a 150cfm fan, I used soil from a specialist and good seeds. During the first month, I used the lamp at 70%, then switched to full power. Now it's almost 2 months and the plants are starting to have problems: the leaves are drying out, they're thin, the plants are very light green and the flowers don't seem to be growing very big... What am I doing wrong? I also gave them some fertilizer, which I never used with the HPS... With only 3 weeks left until harvest, I'm feeling a bit down. Can anyone give me some advice? In theory, my Sanlight should be a better product than any 400W HPS, yet it seems to be going worse.."
Questions for my growbox
- Thread starter megaskunk
- Start date
A pic would dev help.
You didn't mention what light cycle you are using; I veg on 18/6 and switch to 12/12 for flower.
When switching from HPS to LED one needs to raise the hydroxyl content of the water to protect the leaves. LEDs discharge light with intense beams while HPS discharges light in flood waves. Adding cal-mag to your water when switching to LEDs is important. If you don't add cal mag to the RO water or dolomite lime to the soil-mix you will get leaf burn using LEDs. When you added fertilizer the plants declined more because the excess hydrogen made the leaves more fragile to burn causing even more bronzing. If your leaves are burnt you can't do anything to save them.
Every problem is a golden opportunity to learn something and get better. The more the problems you run into the more advanced your skills will become if you work through the challenges. Getting yourself an EC and pH meter will eliminate guessing and confusion. Testing the discharge and the intake liquid can tell a grower what they have or need. Make it easy on yourself friend get the meters and learn how to use them. So easy. Good luck.
Every problem is a golden opportunity to learn something and get better. The more the problems you run into the more advanced your skills will become if you work through the challenges. Getting yourself an EC and pH meter will eliminate guessing and confusion. Testing the discharge and the intake liquid can tell a grower what they have or need. Make it easy on yourself friend get the meters and learn how to use them. So easy. Good luck.
"Thank you very much for your very professional response. May I ask you something else? I am Italian and I am translating with Gemini, so I have trouble understanding the acronyms.
So you recommend that I get a pH meter and a second meter for what? What exactly do you mean? Can you recommend any specific meters?
To provide more information, I am obviously using autoflowering seeds with an 18/6 light cycle."
Thank you!
TDS meter, (total dissolved salts) measures parts per million. or EC meter, (electric conductivity). You can watch the ppm or ec in the soil using one of these meters. I prefer ppm over EC.
I am very grateful for your assistance. Could you please direct me to a resource where I can find a sample table outlining the necessary substances and their approximate quantities for my specific requirements?
From what I understand, using LED lights will require different things compared to HPS, and probably different values. Or is there a standard table that i should respect?
IC GLASS
New member
It sounds like your plants might be experiencing some stress or nutrient imbalances. Even though your Sanlight EVO 5 LED should be a great upgrade, there are a few things to check. Ensure your LED light is not too close to the plants, as this can cause light burn and stress. Also, check if your pH levels are within the optimal range for your soil and nutrients, as imbalances can lead to nutrient deficiencies. Finally, over-fertilization can also cause issues; make sure you're following the recommended feeding schedule. If you adjust these factors, you might see improvement in your plants' health before harvest.
I'm considering the possibility of a thermal shock as well, along with the obvious nutritional issue.
I wonder if, as the seller told me, since the lamp has a power comparable to a 600 HPS, it's worth using it at 80% without necessarily reaching 100%.
Here's what confuses me:
I measure the pH and aim to keep it between 6 and 7, but how do I determine the exact amount and type of substance to add before the problem?
You might suggest "using a meter" but does the meter actually specify which substance is deficient and how much I need to add?
doc_loomis
Active member
Imo, the most important metrics haven't been discussed yet. What's your climate?
Also, as @chilliwilli said, a pic would definitely help with helping you.
And another thing to be aware of, soil is buffering whatever you put into it as nutrients, and you'll probably only see a difference after a week or two. Which is way too late usually. And as @Creeperpark said, once the leafs are burnt/yellow/rusty/not green in any way, you won't get them back.
With soil, you're not really able to steer into any direction. If you don't want to go the pH/ec meter route (which you should in any case), you can go with living soil. I've only heard good things about it, and you just need to add water.
Also, as @chilliwilli said, a pic would definitely help with helping you.
And another thing to be aware of, soil is buffering whatever you put into it as nutrients, and you'll probably only see a difference after a week or two. Which is way too late usually. And as @Creeperpark said, once the leafs are burnt/yellow/rusty/not green in any way, you won't get them back.
With soil, you're not really able to steer into any direction. If you don't want to go the pH/ec meter route (which you should in any case), you can go with living soil. I've only heard good things about it, and you just need to add water.
Hey OP
Coming from HPS to leds its important to adapt to the new light, at high intensity your grow should be at least 26C. With hps this is the ceiling for temps, with leds (on high intensity) ots the floor.
Read up on vapour pressure deficit (though i dont know where youd be able in italian) - this is the way to get your plants to drink properly with leds. No drinking no nutes. Its also very common to have to increase nutes in a led grow. You will defo need a good ec meter to get this right and check both ec of input and output.
I would not recommend solid nutrients in soil for a new led grow it gets too complicated to correct and learn. Go for hydro type nutes.
For vpd charts try vpdchart.com.
Coming from HPS to leds its important to adapt to the new light, at high intensity your grow should be at least 26C. With hps this is the ceiling for temps, with leds (on high intensity) ots the floor.
Read up on vapour pressure deficit (though i dont know where youd be able in italian) - this is the way to get your plants to drink properly with leds. No drinking no nutes. Its also very common to have to increase nutes in a led grow. You will defo need a good ec meter to get this right and check both ec of input and output.
I would not recommend solid nutrients in soil for a new led grow it gets too complicated to correct and learn. Go for hydro type nutes.
For vpd charts try vpdchart.com.
