LED and minimal day/night temp fluctuation

What do you LED folks do about your temps?

I sit at 69-72 lights on and only a couple degrees cooler at night. I don't want to end up with fluffy buds due to low temps and small day/night fluctuation.

Anyone with LED experience can answer, but please specify whether you've dealt with similar temps or not.

Everything looks healthy, maybe a touch on the slow side but I'm still a little concerned.

is this happening cause you're running your lights at night?

if you run them during the day, or stagger them so they turn off early morning, i don't see how its possible to not have a temp fluctuation

edit: i use LEDs. 80-85F on and 70-75F off. my lights run 5pm-5am. from 5am-10am or so it gets down to 70F, but then the rest of my "night" is mid 70s. I dont have more than 5-10 degree fluctuation and fine results.

I like the 78-82 range for growth and quality and never let the temps swing more than 10 degrees from day to night.

pulpoinspace said:

is this happening cause you're running your lights at night?

if you run them during the day, or stagger them so they turn off early morning, i don't see how its possible to not have a temp fluctuation

edit: i use LEDs. 80-85F on and 70-75F off. my lights run 5pm-5am. from 5am-10am or so it gets down to 70F, but then the rest of my "night" is mid 70s. I dont have more than 5-10 degree fluctuation and fine results.

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On 10AM - off 10PM. Temp is low due to exhausting air and pulling new cool air, the exhaust is running as low as possible to retain as much heat as possible.

CBDgold01 said:

On 10AM - off 10PM. Temp is low due to exhausting air and pulling new cool air, the exhaust is running as low as possible to retain as much heat as possible.

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Your house stay at the same temp day and night? Lights should be able to raise it a couple degrees. You could try turning your exhaust fan down

pulpoinspace said:

Your house stay at the same temp day and night? Lights should be able to raise it a couple degrees. You could try turning your exhaust fan down

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my house is a couple degrees cooler at night. I added in an extra light to raise temps. Wasn't necessary but at least it'll warm it up a little bit.

Well with LEDs there's no IR in the first place, so leaf surface temperatures are usually what your ambient temps are. You will find better growth above 80* with LED.

CBDgold01 said:

On 10AM - off 10PM. Temp is low due to exhausting air and pulling new cool air, the exhaust is running as low as possible to retain as much heat as possible.

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where do you pull your cold air from? are your fans dimmed already? maybe you need to reduce your fan size and/or preheat your incoming air. or think about building a heat exchanger to harvest the warmth from your exhaust air to preheat your incoming air

Ive loads of experience growing in the cold. Every winter.
Its not the ideal temps for me now the weather's cooling.
I deal with low temps or should I say the plants deal with low temps ok.
I've a tent that's at 22°C - 71F lights on, 50f lights off.
Another area is 28°C - 82F lights on, 14°C - 57F lights off.
I veg in the coolness too lol
I've never had wispy buds.
They are very versatile plants that can adapt to grow in a wide range of temps I say.

CBDgold01 said:

What do you LED folks do about your temps?

I sit at 69-72 lights on and only a couple degrees cooler at night. I don't want to end up with fluffy buds due to low temps and small day/night fluctuation.

Anyone with LED experience can answer, but please specify whether you've dealt with similar temps or not.

Everything looks healthy, maybe a touch on the slow side but I'm still a little concerned.

Click to expand...

May I ask how many watts you have? With 30-35w / sft. you should get higher temperatures unless you use inefficient blurples or its really cold outside. Then you need 45-50w / sft for temps around 80°s.
You could put the exaust fan on a timer and let it run only 15 mins per hour to keep the heat inside the tent.

sethimus said:

where do you pull your cold air from? are your fans dimmed already? maybe you need to reduce your fan size and/or preheat your incoming air. or think about building a heat exchanger to harvest the warmth from your exhaust air to preheat your incoming air

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Air is pulled in from the floor. Im going to buy a duct fan to pull warm air from above and close the ports. My inline fan is only 4 inch and turned all the way down, but the space is small so its constantly pulling in cool air from below.

The too little fluctuation between night and day temp isn't a thing. Its when you have huge fluctuation that you need to address the issue. Some people have even tried
If your plants are healthy I wouldn't worry too much.

What lights are you using in what space?

Edit I have had temps as low as 70 at lights on, never saw any issue except for plants expressing more colour in some strains.

coreywebster said:

The too little fluctuation between night and day temp isn't a thing. Its when you have huge fluctuation that you need to address the issue.
If your plants are healthy I wouldn't worry too much.

What lights are you using in what space?

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20x36x60 inch space (1.8x3x5 foot) I have a 160W QB that can go up to 185W. I added a 130 true watt blurple mainly for extra heat.

CBDgold01 said:

20x36x60 inch space (1.8x3x5 foot) I have a 160W QB that can go up to 185W. I added a 130 true watt blurple mainly for extra heat.

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Cool, just checking we were not talking some magical "1200w grow light" that only has 135w..

I have a couple of the 260w kits myself.
Daft question but did you check when you plugged her in she was turned all the way up (if the driver has built in dimmer like mine)?

You shouldn't get airy buds due to low temps, if you get a problem it will likely be a deficiency.

Do you vent your heat directly outside the house?

coreywebster said:

Cool, just checking we were not talking some magical "1200w grow light" that only has 135w..

I have a couple of the 260w kits myself.
Daft question but did you check when you plugged her in she was turned all the way up (if the driver has built in dimmer like mine)?

You shouldn't get airy buds due to low temps, if you get a problem it will likely be a deficiency.

Do you vent your heat directly outside the house?

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No, fan is vented back into the ~15x15 room the tent is in. Its turned all the way up, the temp of my house is only like 70 during the day. I spent like 5-6 hours today rearranging the tent trying to get temps up... back is killing me lol. Now air is drawn from above the tent where its warmer (was pulling air thru floor vents) and I am getting temps of 75-78. Lights out will be ~66-67. not much else i can do now.

Hi, I have exactly the same issue- live in a cool climate, and once past Sept I start running into issues. A friend deals with it by using a heat - mat underneath his plants, and I have a 30w "greenhouse" heater that I can leave on night an day and uses very little power. Running a 300w Mars Hydro in a small tent, but needs extra heat

CBDgold01 said:

whether you've dealt with similar temps or not.

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I`m glad to have built a watercooled led light -

with summer outside temps. close to 38°C (100°F) most of indoor growers have problems with too much heat.
If then you are able to transport a big part of the produced heat to the outside of the grow room
without additional electricity - you can be happy.

With my watercooled light i can store 80% of the produced heat in my heatexchanger and it leaves my household by the sewer pipes of bathroom, kitchen and washing machine.

If i want my babies to stay cool in summer nights - i empty the boiler after the light cycle
and cool incoming water (17°C) is running through my heatsinks and the temps. inside my chamber are quiet lower than inside the rest of the flat.

In winter times it`s going vice versa - and i can bring back heat to my chamber if i want.

Getting temps up to 85 degrees lights on now on warm days. Not sure if this is too warm

add more lights.

facthunt said:

in a small tent

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small is good - but a solid, well insulated chamber with a reduced min. airflow will help you to keep higher temps.

real 300W led-light still means ~225W (~75%) of produced heat + ~75W(~25%) light, which then is converted to heat on the surface of the inlighted area, if it doesn`t serve for photosynthesis.

Avoid cool incoming air blowing onto wet roots. Keep them as dry as possible .They are the most sensitive part of a plant against cold. The micro-organisms don`t like it cold either
and insulating the bottom of your pots with a piece of rigid foam can help to keep them more activ.

In summer it`s good to have the incoming air at the bottom and outgoing at the top.
In winter you should use some meters of fan pipe to manage your airflow vice versa.

Some growers using the heat of the outgoing air to heat up the ingoing air with a selfmade heatexchanger.