hps to led problems

danzibar1

Active Member
hi all, after years of hps i decided to buy a led 720w ,so i have 2 wilma systems side by side, one with 600 hps and the other using my new led 720w
they a both 4 weeks into flower,and both getting tret exactly the same ,nutes,watering times etc
the plants under the hps are fine,and looking really healthy,but the ones under the led light are looking a little lime green and a bit veiny
could anyone help im 4 weeks in to flower,they are not in tents,but both in the same room
il try and get sum pics
Similar ??
 

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Drasik

Active Member
It could also be the LEDs aren't heating the leaf surfaces and the lower transpiration of the plants is reducing nutrient uptake.

You can check your canopy PPFD with a free app like Photon, 800-1100 is usually the sweet spot for flowering.
What this man said check the leaf temp on the gun first if its low, you can let ur rooms get a bit hotter but then it might affect the plants under HPS(we never do mixed rooms lighting, your essentially using to different processes)

He is also right, 800-1100 is that sweet spot during flowering. You can push light harder but then you have to ensure that your pushing the plants metabolism higher( more c02, more feed).

If your really dedicated buy yourself a quantum meter you can get a decent one for as low as $300-400. Those apps can never give you an accurate reading, they don't have quantum sensors built in and they only can infer PPFD.
 

Greenman71

Active Member
HPS lights have frequencies most LEDs do not, or very little of. LED companies think just because a wavelength isn't photosynthetically active they are not important, so they generally don't put UV or IR diodes in their lights. I've come to the opinion that UV and IR are very important to plant growth. After switching to lights with a good amount of UV and IR, I have noted faster growth, better side branching, faster flowering and increased terpene and trichome production. Could be your switch to LED has shocked your plant a little. If they were used to the HPS light with its broader spectrum, your plant might feel its being deprived of light.
 

farmingfisherman

Well-Known Member
HPS lights have frequencies most LEDs do not, or very little of. LED companies think just because a wavelength isn't photosynthetically active they are not important, so they generally don't put UV or IR diodes in their lights. I've come to the opinion that UV and IR are very important to plant growth. After switching to lights with a good amount of UV and IR, I have noted faster growth, better side branching, faster flowering and increased terpene and trichome production. Could be your switch to LED has shocked your plant a little. If they were used to the HPS light with its broader spectrum, your plant might feel its being deprived of light.
Who's lights are you running?
 

danzibar1

Active Member
Raised my temps to 27 increased my watering and turned down light percentage they bounced back in a week

no new veg had any of the deficiency’s and some old leaves have not fully recovered even leaves lower down

so I’m thinking maybe the plant was deprived of a nutrient that’s not mobile hence why some leaves have not recovered

or the light stress does not fully recover
 

farmingfisherman

Well-Known Member
Raised my temps to 27 increased my watering and turned down light percentage they bounced back in a week

no new veg had any of the deficiency’s and some old leaves have not fully recovered even leaves lower down

so I’m thinking maybe the plant was deprived of a nutrient that’s not mobile hence why some leaves have not recovered

or the light stress does not fully recover
Another mystery solved.
 

Star Dog

Well-Known Member
Raised my temps to 27 increased my watering and turned down light percentage they bounced back in a week

no new veg had any of the deficiency’s and some old leaves have not fully recovered even leaves lower down

so I’m thinking maybe the plant was deprived of a nutrient that’s not mobile hence why some leaves have not recovered

or the light stress does not fully recover
Nutrient deprived sounds feasible to me, all else being equal I've got to use a higher ec using led (1.4/1.8ec) than with hps (1.2/1.4ec) in flower.

I used hps for a few years without any nutrient problems but i need to increase the ec when i swap lights or increase the led intensity.

Last week the day after I increased the power i could tell something wasn't right when I tested the run off it was down at 0.7ec from 1.4ec I've since increased twice its now 1.8ec and everything looks fine. DSCF4009.JPG
Leaf surface temps have been well off since day #1 24c-25c ambient is the best temps I've had with this crop and that's only due to increase in power it was previously 22c-23c.
 

farmingfisherman

Well-Known Member
Nutrient deprived sounds feasible to me, all else being equal I've got to use a higher ec using led (1.4/1.8ec) than with hps (1.2/1.4ec) in flower.

I used hps for a few years without any nutrient problems but i need to increase the ec when i swap lights or increase the led intensity.

Last week the day after I increased the power i could tell something wasn't right when I tested the run off it was down at 0.7ec from 1.4ec I've since increased twice its now 1.8ec and everything looks fine. View attachment 5210311
Leaf surface temps have been well off since day #1 24c-25c ambient is the best temps I've had with this crop and that's only due to increase in power it was previously 22c-23c.
Looks tropical!
 

curious2garden

Well-Known Mod
Staff member
Raised my temps to 27 increased my watering and turned down light percentage they bounced back in a week

no new veg had any of the deficiency’s and some old leaves have not fully recovered even leaves lower down

so I’m thinking maybe the plant was deprived of a nutrient that’s not mobile hence why some leaves have not recovered

or the light stress does not fully recover
Even with mobile nutrients leaves tend not to repair themselves. The usually only shift upward.
 
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