Can I switch from HPS to LED

[Unclechro]

Hi all, I have just germinated 3 x autos direct in soil under my 600w HPS but dialed down to 250w and about 1 metre from the top of the pots so they dont get too hot.  They are a couple of days old now and look like they could get leggy if I leave the light so far away.  I wondered if it is OK now to swap my HPS for my LED which I can have a lot closer (approx 10 inches) so would stop them from getting leggy but wasn't sure if switching lights would freak them out at all ?

[Devon Cream]

Your be fine doing that pal.

[Shumroom]

As Devon Cream said,

you’ll be fine  

 

A heat mat with thermostat control might be necessary with the LEDs though 

 

Atb

 

 

 

[Unclechro]

Thanks chaps i will get them swapped over and yes i do need to have a bit of a think about heat as running my LED at 40% for the seedling stage doesn't get them much heat at all so dont want them shivering. I have a small thermosatat controlled heater i can use but might also get a heat mat as well as that will use a lot less electric,  just until they are into vegging and I can crank up the LED to 100% and provide radiant heat, cheers.

[Lux_Interior]

 As @Shumroom mentioned don't expect your LED 'even cranked up' to produce any thing like the heat of a 'good'ol HPS', it was a culture shock for me. I moved my groom out of the loft and into warmer room. Economically it made sense.

 

Welcome to UK420 by the way dude!

 

 

[darksecrets999]

9 hours ago, Lux_Interior said:

 As @Shumroom mentioned don't expect your LED 'even cranked up' to produce any thing like the heat of a 'good'ol HPS', it was a culture shock for me. I moved my groom out of the loft and into warmer room. Economically it made sense.

 

Welcome to UK420 by the way dude!

 

 

I’d like to add to this. HPS lights radiate heat downwards. When you put your hand over the top of the reflector you don’t feel much heat. When you put your hand under the light it’s a whole different story. Whereas with LEDs they seem to do the opposite. Radiate heat upwards away from your plant canopy. 
 

I find blowing a fan over the lights downwards pushes the heat down to your plant canopy helping create a more healthy environment for your plants. Still not as good as HPS but every little helps

[Goodbloke]

Agree re fan above LED pointing down. Measured a canopy level temp rise with a fan. 

[Military Grade]

How I had mine over winter, not needed now in my Setup since weather warmed up, I also have two small tube heaters on the floor.

[Unclechro]

@darksecrets999 @Goodbloke @Military Grade - Fantastic advice, i will sit my clip fan over the top of my LED if heat is an issue to push down onto the pots, i also ordered a tube heater just in case. Hopefully with the weather warming up a bit now I won't need it too much but i will at least be ready for next winter.

[Military Grade]

I use a thermostat with probe one for both tube heaters and one for my heat mat, helps keep the temps as desired.

[Goodbloke]

Same setup as @Military Grade, sensor in the pot for heat mat & sensor in the grow space for the tube heater. 

[DutchFox]

On 24-3-2023 at 10:52 AM, darksecrets999 said:

I’d like to add to this. HPS lights radiate heat downwards. When you put your hand over the top of the reflector you don’t feel much heat. When you put your hand under the light it’s a whole different story. Whereas with LEDs they seem to do the opposite. Radiate heat upwards away from your plant canopy. 
 

I find blowing a fan over the lights downwards pushes the heat down to your plant canopy helping create a more healthy environment for your plants. Still not as good as HPS but every little helps

 

with hps...you nomally suck the hot air away from above...the ( passive) inlet of fresh colder air is from below.

 

with led....you better suck the air away from the bottem..( use inline filter..easy to make diy ) ...and the ( passive)  inlet from above....so you force the air down....and the warmth offcouse too....  

Edited March 25, 2023 by DutchFox

[Unclechro]

10 hours ago, DutchFox said:

 

with hps...you nomally suck the hot air away from above...the ( passive) inlet of fresh colder air is from below.

 

with led....you better suck the air away from the bottem..( use inline filter..easy to make diy ) ...and the ( passive)  inlet from above....so you force the air down....and the warmth offcouse too....  

That's a really interesting idea for the colder months to draw that warmth down rather than up, never heard of that but makes complete sense, great idea.

[Goodbloke]

I noticed a better increase in canopy temps keeping top extraction but adding an over light fan compared with bottom extraction & no fan. Ambient could have been a factor though. 

No room in current setup to run the extract ducting to low level so using top extract + horizontal fans. 

[Unclechro]

1 hour ago, Goodbloke said:

I noticed a better increase in canopy temps keeping top extraction but adding an over light fan compared with bottom extraction & no fan. Ambient could have been a factor though. 

No room in current setup to run the extract ducting to low level so using top extract + horizontal fans. 

I will have ro test out the different methods. A bit of a change in topic but this is my first time in small tent with LED, running a 2.5ft x 2.5ft x 5ft and wondered what people did about fan placement. I always had room before for a floor standing oscillating fan but being so small any suggestions of what sort of fan and where I coukd place them, I was considering a tower fan tucked in a corner ?