LED and dehumidifier light on

[Rhizoma]

Hi all,

Can you help me to understand this?
I would like to switch from 250 HPS to 250 LED.
My main concern is humidity during flowering.
HPS arrive to keep humidity more or less in range during light on.

Would LED do the same for all the flowering stage?
RH lung 65-70%
RH tent now 55-65%
4 week flowering


Thanks

 

[GMT]

If you are attributing the reduction in humidity to the heat generated by your hps, then you won't get that same heat from LEDs.

 

[Rhizoma]

If you are attributing the reduction in humidity to the heat generated by your hps, then you won't get that same heat from LEDs.

And how do you compensate?
Extra heat? Or extra dehumifier?

 

[Creeperpark]

I use a dehumidifier when the lighting is only LED in small areas. When I have plenty of space I use both lights as a combo if the plants are already used to the HPS. Adding an LED to a HPS will give robust growth with fatter buds.

 

[GMT]

I use airflow, it achieves the same thing for lower running costs.

 

[Rhizoma]

I use airflow, it achieves the same thing for lower running costs.

Could I ask you to explain a bit better?
Extraction or fan? Do you achieve to drop humidity down or the first is enough to prevent mould?

 

[GMT]

I swear I'm not trying to be clever or arsey with this response, just a bit confused on the difference. I extract with the fan? It sucks the air out of the tent and blows it into the room. The room (on the odd occasions that it's not raining) has an open window, and when it's raining, the door to the rest of the house is open.
The higher the airflow, with the aid of a touch of silicon, prevents mould (normally), from forming. I can't talk about humidity really as I've never measured it in 27 years of growing, I really should get a thingy-gizmabob to do that.

 

[Koondense]

If you can keep the lung room at 60-70% it will be fine with leds.
They won't heat the leaves as much as hps so maybe there's a bit higher chance for condensation on/under touching leaves but nothing too concerning imo.
Just get them enough fresh air and they'll be happy.

Btw, what are the temperatures?

Cheers

 

[X15]

I use airflow as well via extraction inline fan, ported out of the room. It saves on electricity. Something you may find with a dehum is that they can add heat to the room as well. So you will be tinkering a lot more and using more electricity. If that isn’t an issue dehums work great.
I just believe growing anything should be as low cost as possible.

 

[Rhizoma]

@GMT Many thanks for the info, very much appreciated.
@Koondense: I can keep that RH with dehumidifier
@X15 : bills is my big concern...and particularly the dehumidifier which I try to use only at light off and last weeks of flowering.

The point of opening the window is a problen that I need to solve as I don't have enough passive opening to take fresh air. Maybe an intake from outside into the pre lung-room?

Thanks all for the advises.
I guess after this grow I will put the LED up and from there see what I have to do. Happy to see there are cheap solutions
Tx

 

[Rocket Soul]

A cheapo rh+ solution: container with water with a towel or similar hanging above the container, dipping part of the fabric into the water. Place a fan behind which dries the towel while the towel will continuously draw up more water.

But you would still have to add some heat to the space, leds dont tend to like cold, need heat for transpiration (read up on VPD for this) and for just general metabolism. This is the biggest hurdle when starting out with leds: to get around to what used to be a higher limit for temps (around 79F) is now the new lower limit for leds at high intensity.

 

[Gman 420]

A dehumidifier in the lung room should keep things in check or even a small 2ft 80w tube heater in your tent would help, a good quality 250w led should yield double a 250w hps once you have ur environment dialed in

 

[Rhizoma]

A dehumidifier in the lung room should keep things in check or even a small 2ft 80w tube heater in your tent would help, a good quality 250w led should yield double a 250w hps once you have ur environment dialed in

With HPS 250...( I am quite a beginner) I won't able to yeald more than 0.3-0.5gr/watt....
I hope after this grow with LED I can achieve better results.

 

[Rhizoma]

Adding an LED to a HPS will give robust growth with fatter buds.

This would be actually a terrific idea which could allow me to use LED also during winter and replacing the need for heat with extra light....so adding a 150w HPS to a 280w LED.
Replacing 135w tube heather with a 150w hps.

I guess that one of the reasons why I am not achieving never good yeald is because very little wattage In big areas (2*4) with lot of plants ( 8*6l). Maybe I should reduce number of plants and increase light?
Something I am still doing wrong

 

[foomar]

Useing three cheap but decent quality leds of Amazon in a 4 by 2 tent for a few years now.
Run at 80% nearly all the time so 240 watts total.
I like to squeeze as many in as possible.

Four plants in 10 litre pots 250 gram
Twelve plants in 5 litre pots 275 gram
Eighteen plants in 3 litre pots 300 gram (mould magnet)
Forty five plants in 2 litre pots 300 gram (never try this again)
Same veg and MBS clone , average yielder.

Sorting out the canopy temperature was by far the most important tweak moveing from HPS.

Swapping out the central led with a 150 watt hps in a cold winter works really well.

 

[Mr Jay]

A dehumidifier in the lung room should keep things in check or even a small 2ft 80w tube heater in your tent would help, a good quality 250w led should yield double a 250w hps once you have ur environment dialed in

Just to be clear since OP is new to LED, this means if the new LED draws a true 250W and is not a 250W equivalent. The "Equivalent" rating is usually wildly inaccurate, one should go from true draw.

I like to ramp up my extraction fan so my tent RH is kept ambient with the room it is in. We have dry summers here, but winters are very wet and if I want to grow I have to run a dehumidifier in the room. It's fine though, that's just a bunch of chlorine free water I can feed back to my babies.