Hps + mh light heights

Hey guyz im New here all the way from S.A,please if anyone could help me i have just purchased a hps +mh grow kit,my main worry is how high do i adjust them for seedlings and there after,i have read a few places 30cm but that is crazy low,please help thanks guyz,One love

Heat is the biggest issue with MH/CMH/HPS.

Lights are too close when you can feel the heat on the back of your hand when your hand is held at the tips of the plant. Anything else pretty much goes.

One thing to watch for when learning to place light height is node spacing. Too little light results in a spindly plant. Too much light results in an overly compact plant. Cannabis responds very well to light adjustments in terms of this. You will get a feel for it over time.

I grow with LEDs, so I can’t give guidance on specific light heights, but there are a few growers here that do. Perhaps one of them can chime in with a specific recommendation.

You may find this thread helpful too:

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You don’t say the wattage above.
400,600,1000 w.
I’ve got 2 x 600 and a 1000 w.
I’ll start introducing them at 3 ft plus above the seedlings to harden them off a bit , then lower every couple days till I get to 20 in above.
Watch ur canopy temps as mentioned above.
Keeping lots of air flow under the lights will help with some of the heat generated.

For just starting the seed I’ll use a t-12 x 4 tube 4 ft fixture for the first couple weeks.
They don’t need a lot of light at first.

Happy growing.
:v::call_me_hand:

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Hey oldguy that helps a bunch ,i got a 400w mh and a 600w hps,the current height light to pot ia 1.10 meters i had it on for a few minutes the heat is crazy, 3ft is almost a meter after that i dont have much space to raise it,will this be a problem in the future or can i leave it like that for the entire grow?really stressing if i can raise it further.

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Thanks Midwest that also helps a bunch.

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Photone is the app on your phone. It is great to have and help with the DLI and PAR . It makes things much easier

@Mewa.352

Just to be clear. 2 ballasts right ?
Bulbs aren’t interchangeable.
They Have to be sized to the ballast.
If the ballasts are digital you should be able to turn them down a bit at the start but you’ll still need to match the bulb to the ballast rating.
My 1k has to be at the top but not dimmable. Bout the same as you with 1.1 - 1.2 m clearance.
My 600’s I can dial down so start them a bit closer at about 50% then adjust from there as they grow.

You’re going to need an exhaust fan big enough to get rid of the excess heat but it’s very doable.
I run a 10 in exh fan in my 11 x 14 room. With a couple 16 in oscillating stand up fans aimed over the canopy.
I can keep it close to 82 ish f for the most part.
If I run the 1 k with the rest on a warm ish day it’ll creep up a few deg over that but not too bad.
Lil bigger intake would help.
Work in progress. :wink:
:v::call_me_hand: