Leaf curl

Hi All, very baffled as some of the leaves on my plants are curling up as if they struggling with heat stress.

This baffles me as the temp at the tops of the plant hasnt rose above 29degress once, iv soent wuite alot on kepling my tempreture stable and it has been...

A couple of days ago when i noticed the problem my lights were only 16” away from the plants so i rose them to 19”s away.. but the problem is still getting worse..

My lights are only set at 400 watt wach. PH is good, have two circulating fans, intake, AC input, and out take fan. Negative pressure always.

I will admit that my themometer is saying my res water is 22-26 degrees, but it feels cool to touch so not sure if this is an issue? Humidity is 30 without humidifier and 45 with (hard to keep on top of this) and i was worried that because i only keep on top of hunidity during light hours that the steam was going onto the leaves directly and thats why the lights may have been drying them out so i have left humidifer off today as a trial but still getting worse.

Now have 2 large buckets of water in there to try boost humidity up but thats done nothing?

Any help will be much appreciated

Raise the lights to 2' and get air moving over and around. Steam? Plants transpire water via the leaves at far higher temps. This is heat from above.

Ok mate so i have just raised my lights so ther 2ft (24inches away from the plants) i always thought 18” was what people normally go for. There are two fans blowing directly to the tops of the fans from bothe ends, one is a monkey fan that sways side to side, i have raised them now so its blowing into that canopy area alot more, turned the one fan up also.

Sorry when i say steam i mean the vapour from the humidifier, so you dont think that should cause a problem and i should get as much humidity in there as possible at this stage?

Thanks for input mate, hopefully i can crack this problem asap before i stress them out too much, never had this before and on previous crops my temps been all over the place! This is the one where iv got the temp spot on and consistant.. and the plants are cooking :-/ never had a tent this cool before whuch is so frustrating

That water temp would worry me....22C is tolerable, but anything over that and I'd consider either a chiller or adding beneficials. And how high is your RH? If the humidity is too high, the leaves can't transpire water as efficiently as they need too, especially at stages where the plant is larger in size. That definitely looks like classic heat stress though.

Water temp is 22 degrees on a morning after 6 hours of no light, throughout the day it increases to 25/26 degrees (according to the themometer) i dont really trust it though as it feels cool, it feels drinkable if that makes sence? Dont worry i wont be drinking it unless someone tells me i can grow buds lol!!

Im a bit of a newby so not sure what RH is so i do apolagise?

I have just ordered a decent themometer to check im getting the correct reading on the res.

Wouldnt you say my humidity is low at 30-45% during veg stage i thought i need to get that higher if anything?

Thanks again here to learn

Oh it's ok man it's never to late to get into growing! RH just means your relative humidity %, moisture in the air And at the stage you're at in veg, as long as you have a strong root system on the plant, 30-45% should be just fine. When they're babies and don't have much root mass, they do need higher humidity to keep from losing the water I uptake as quickly. But once a strong root system is developed, it's not necessary, and even stressful. Do you have a fan blowing over the canopy of the plants?

Ahhh learn something new everyday, yes i have two fans blowing, up until now they was blowong more directly onto the plants from both ends of the tent but i have just raised the lights so there 2ft away from the plant tops, and raised the fans so they are blowong into the canopy area alot more than before..

Ill leave the humidty off for now, if they continue to get worse from today onwards after i have adjusted fans and raised the lights another 5 inches... ill find it really hard to believe it can be the heat causing the issue. Tips of the plant area has never reached 30 degrees as it is! All my other crops iv done, i have gone in the tent and found the temp to be 40+ got it down then few days later its up again... iv really spent some Money on improving my system to resolve this issue and keep temp stable and its worked, but the plants have not appreciated my efforts lol!!

Akadan77 said:

Ahhh learn something new everyday, yes i have two fans blowing, up until now they was blowong more directly onto the plants from both ends of the tent but i have just raised the lights so there 2ft away from the plant tops, and raised the fans so they are blowong into the canopy area alot more than before..

Ill leave the humidty off for now, if they continue to get worse from today onwards after i have adjusted fans and raised the lights another 5 inches... ill find it really hard to believe it can be the heat causing the issue. Tips of the plant area has never reached 30 degrees as it is! All my other crops iv done, i have gone in the tent and found the temp to be 40+ got it down then few days later its up again... iv really spent some Money on improving my system to resolve this issue and keep temp stable and its worked, but the plants have not appreciated my efforts lol!!

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His @LoganBurke advice on a chiller - start researching and getting something together for the job. Do this long enough it will be mandatory. Speaking from Alaska and from experience .

hotrodharley said:

His @LoganBurke advice on a chiller - start researching and getting something together for the job. Do this long enough it will be mandatory. Speaking from Alaska and from experience .

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Thanks mate will look into it, will check if my readings are correct when i get an improved themometer though first

Akadan77 said:

Thanks mate will look into it, will check if my readings are correct when i get an improved themometer though first

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A chiller will allow you to sleep. The first time you get root rot you'll see.

Akadan77 said:

Thanks mate will look into it, will check if my readings are correct when i get an improved themometer though first

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Look into using an old dehumidifier to make one.

Yeah i dread that. Root rot gives me nightmares, this is my first hydro grow aswell, all previous have been soil, I have never seen a chiller or how ther work, As i have 3 seperate tanks/reseviors i wonder how i could cool 3 areas with one chiller?

The worrying thing is the water tempt problem can only get worse as i have another 200/260watts left on each light (x3) to go up to yet as the plants get stonger

There are a few simple things you can do for water temps. I keep a small clip fan blowing on my airpump at all times to help the air cool off and the pump cool off too. You can also wrap your water containers in some type of mylar/reflective material so that the buckets/containers don't absorb nearly as much of the heat. Some of these things may help until you decide on a long term solution.

Well just as you say that i hve some 4mm sheeted wood in the garage, i have just taken measurments to cut some pieces up and them ill buy some black out and wrap the sheets (white side up) to reflect the light, at the minute im just using bin liners which will probably be absorbing the heat as its black, im not aure how kuch of a difference this can make but ill be changing this tomorrow and will do a res change at the same time and ill let you all know if it helps

Good luck man sounds like you've got a game plan.

Logan Burke said:

There are a few simple things you can do for water temps. I keep a small clip fan blowing on my airpump at all times to help the air cool off and the pump cool off too. You can also wrap your water containers in some type of mylar/reflective material so that the buckets/containers don't absorb nearly as much of the heat. Some of these things may help until you decide on a long term solution.

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Great advice here. I have my waterfarms wrapped in reflectix and a layer of reflectix sits on top of the hydroton to reflect light from heating up the balls. I run my lights at night now which has helped also. My rez temps stay around 68-71f and I proactively use hydroguard to keep roots healthy. I'm working on adding an airstone this weekend which also promotes root health via oxygen. It's all about the roots in hydro, keep that in mind.

Thanks Mike, never even thought to cover the balls aswell, iv been advised to get silver bullet, quite pricey mind, is hydroguard a similar product? Need to order something today to protect the roots as have nothing in the res cutlrrently. 2 air stones in each res already on my setup,

Got me thinking about buying some reflectix now, sounds a good idea as will bounce light back up to the bottom buds later on when they get wild, its just i have a friend with tonns of blackout and he suggested to use that but white side up.. might guve that a go first as money is a bit tight at the minute

Akadan77 said:

Thanks Mike, never even thought to cover the balls aswell, iv been advised to get silver bullet, quite pricey mind, is hydroguard a similar product? Need to order something today to protect the roots as have nothing in the res cutlrrently. 2 air stones in each res already on my setup,

Got me thinking about buying some reflectix now, sounds a good idea as will bounce light back up to the bottom buds later on when they get wild, its just i have a friend with tonns of blackout and he suggested to use that but white side up.. might guve that a go first as money is a bit tight at the minute

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One thing I learned is reflectix is good for its purpose, insulation/reflective but struggles with salt residue. Eats through the reflective material and exposes the bubble insulation in some areas. I'm going to use something different my next go. For you, use what you have on hand first before you go buying other stuff. What you have may work just fine. The purpose is to keep the heat from being absorbed. Reflection is not important directly underneath the plant itself as it'll have no real effect on your plant. Underside of leaves do not absorb light, you're just trying to keep the heat off the hydroton.

First time with hydroguard, I feel it's good and works. It has a 6 month shelf life though once opened. I've done some research and spoke with a few growers who swear by Southern AG fungicide. More concentrated and has longer lasting affects than HG according to what I've read. I'm going to purchase this next for my next grow so I recommend it but don't have personal experience with it. I think it's cheaper than hydroguard to, might have to cross check that though.

Keep us posted on your changes. Always interested to see results on different ideas.

I'm fighting with 70%ish RH right now because my cab is at the mercy of outdoor weather. It's in my garage. Costco sells a plug-in dehumidifier I'm going to give a shot. I started my grow first 3.5 weeks around 35-40% RH until I was able to adjust the fan and ventilation combo just right to allow it to creep to 50% it's been raining for days which is why I've got this going on. Don't stress about RH to much though. Mold grows in a stagnant and still environment. Keep that air moving, play with fans and ventilation exchange a little and you may be able to gain 5-10% higher RH w/o humidifier.