Unsinkableship420
Active Member
Hey mate, been putting it in at 6.1ph.
Problems since switching to leds
- Thread starter Unsinkableship420
- Start date
Unsinkableship420
Active Member
So i managed to get out there for this mornings feed and test runoff. Going in 0.9ec 6.1ph , coming out 0.6ec 6.1ph . Noticed considerable bud deveopment as well.
So they are finally feeding again!! Thanks for the pointers boys, you guys rock!! Its nice to find a pot forum where leds are embraced! Haha, i asked for help on another forum and got nothing but replies of go back to hps ect ect.
So they are finally feeding again!! Thanks for the pointers boys, you guys rock!! Its nice to find a pot forum where leds are embraced! Haha, i asked for help on another forum and got nothing but replies of go back to hps ect ect.
Randomblame
Well-Known Member
I would recommend to get a IR thermometer gun to check leaf temps and one or better two temp/humidity meters to check the humidity just below the canopy and above to get an idea of the actual humidity around the plants.
As you can see, only one 1°C less has a huge impact on VPD. I've usually -2° after 1h and -1° at the end of the day and since I'm using the -1° chart I have no issues anymore.
Pretty sure, when you get it in check you can go as high as before in terms of nutes.
Nevertheless using additional calmag and silica is still a good idea with such an amount of light.
As you can see, only one 1°C less has a huge impact on VPD. I've usually -2° after 1h and -1° at the end of the day and since I'm using the -1° chart I have no issues anymore.
Pretty sure, when you get it in check you can go as high as before in terms of nutes.
Nevertheless using additional calmag and silica is still a good idea with such an amount of light.
Last edited:
Randomblame
Well-Known Member
Sorry, mate! But the later is nonsense!
Plants under intense LED light will actuall need more nutes. With a 600w HPS you get ~500 - 600μMol/s/m² depemnding where you measure, with "good" LED 30w/sft is already above that and delivers at least 800μMol/s/m². With 40w/sft it's already up to 1000!
When humidity and temps are in a good range (according to the VPD charts) plants use more water AND more nutes!
Only when the VPD is too high you need to lower the nutrient strength accordingly. Lets say you normally use 1000ppm at 30°C/65% RH and your humidity drops to only 55% for some reason. What will happen?
Because of the higher VPD plants take up 10-15% more water and therefor also take up more nutes!
So to avoid problems with over-fertilization the nutrient strength should be reduced by about 10-15%. The plants can take up and transpire more water but still get a healthy dose of nutriens.
The reason why you experienced less nute consumption is not because of LED light; it's because your Mars lights are rather weak and the intensity is probably not even 500μmol/s/m². Logically, that you needed less nutes with such low intensity.
Can I ask which Mars light it is and how big your area is?
That's what a well known member of this forum has done with his mars lights as he realized that Mars lights are of lower efficiency than hps. And this was already a few years ago when white quality COB's reached ~2,0μMol/J. Now we are in the range around 2,5μMol/J and the best available Mars light currently(1 Cree COB and a few XPE's) has just below 2,0μMol/J.
...but at least the case quality and resilience is amazing, lol!
Last edited:
RetiredGuerilla
Well-Known Member
The Kelvin rating of your bulbs is what determines nutritional demands. A high Kelvin rating like you have with metal halides are good for vegetative growth so this will make your plants hungry for nitrogen as well all the other trace minerals cannabis loves while making leaves and branches.