Heat stress or light stress? With a cool tube ?

I'm using 400w super hps with cool tube and blue side reflectors.

Currently no fan or ducting going through the cool tube but, have a single fan flowing over all 4 plants, temps are fine 25-30 degrees, 45-50 percent humidity, in a 1.2x1.2x2m grow tent. Light is 14" away from tallest plant, critical cheese (auto) roughly 17" for the smaller phenotypes,
img 1. Dutch passion seeds think different (auto)
Img2, Critical cheese (auto) .
img3. ice bomb (phenotype)
img4. White Widow x Big Budd (Phenotype)

but All are showing some signs of heat or light stress/burn?

30C is a bit high, imho...it looks like some heat stress to me, but it's hard to tell under that lighting. Can you take pics using the camera flash as the light source, or under white light?

mc130p said:

30C is a bit high, imho...it looks like some heat stress to me, but it's hard to tell under that lighting. Can you take pics using the camera flash as the light source, or under white light?

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sure here i hope this helps.

Idk man, it's hard to say without more details. I still think it looks a bit like heat stress. I wouldn't go to 30C without CO2 supplementation, and then I'd keep it short. I keep my temps 24-27. I don't think your cool tube is very cool with no air flow, as you said there was no fan or ducting to it.... What kind of nutes are you giving the plants?

mc130p said:

Idk man, it's hard to say without more details. I still think it looks a bit like heat stress. I wouldn't go to 30C without CO2 supplementation, and then I'd keep it short. I keep my temps 24-27. I don't think your cool tube is very cool with no air flow, as you said there was no fan or ducting to it.... What kind of nutes are you giving the plants?

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their 17 days old, ive only fed them once with canna terra vega, quarter the recommended dose. 2 days ago

could it be hot spots how do i find them? would moving them from directly under the light(meaning light hanging overhead i moved it from 17" to about 27" away from plants) temp is running 29c i have opened some little vents at the bottom of the tent for extra ventilation. hope it helps. any other way to lower temps? ( waiting for cool tube attachments )

anyone got idea's to help me out?

so you got a cool tube with no ventilation hooked to it? Thats not a cool tube thats a hot tube! I see you say your waiting on cool tube attachments hope thats a inline fan. To lower temps id try to lower ambient temps outside of tent and open all the vents on the tent until you get fan. Plants look heat stressed but not to bad.

Just trying bringing the highs down a lil, if it's not constant then i really see nothing to worry bout.

booms111 said:

so you got a cool tube with no ventilation hooked to it? Thats not a cool tube thats a hot tube! I see you say your waiting on cool tube attachments hope thats a inline fan. To lower temps id try to lower ambient temps outside of tent and open all the vents on the tent until you get fan. Plants look heat stressed but not to bad.

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I see, thanks for the information, I will open all vents and get some fresh colder air in the room, one more question while the lights Are off 18/6, am I able to have leave my lamp on during the dark period, ( no direct light on any plants ) their may be a little light entering the tent but Not on plants?

Having a light source still in room that plants can "see" will make them stretch towards it and the dimmer the light will make the new stretch it causes weak.

booms111 said:

Having a light source still in room that plants can "see" will make them stretch towards it and the dimmer the light will make the new stretch it causes weak.

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is that a bad thing? if it stretch a little ( light is very weak inside tent almost doesn't make it to the bottom were the plants are ) wouldn't that make the smaller auto's larger? and can i still lst trim or prune autos? 18 days in, pre flower bud sites i believe.?

Micke930 said:

is that a bad thing? if it stretch a little ( light is very weak inside tent almost doesn't make it to the bottom were the plants are ) wouldn't that make the smaller auto's larger? and can i still lst trim or prune autos? 18 days in, pre flower bud sites i believe.?

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id recommend against it. they would get larger in a stretched out bad way

booms111 said:

id recommend against it. they would get larger in a stretched out bad way

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okay ill try take all measures to keep them in darkness, thanks.