Anyone Still Using MH and HPS?

Discussion in 'Lighting' started by PufferLungs, Feb 12, 2023.

  1. How are the LEDs compared to the old school MH and HPS stuff? I have the older gear and I've used it with great results. Thinking about buying some LEDs for a new tent.

    How do I size the LED light for a 3x3 veg tent? If that were HPS I'd use 400w. Do I need to put 400w real watts of LED in there to get the same result?
  2. 35 real watts per square ft is a basic guideline. For just veg, 200 watts should do in 3x3
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  3. I run an SF-4000 LED board in a 4x4 space, does more than enough to fill the area with decent buds imo.
    GG4 photos above, Bruce Banner autos below
    Think this was Gelato and maybe a Jack Herer or two photo

    I've also had similar results with smaller LED (like TS-1000 by mars hydro) in smaller tents.

    I do find that topping and trying to keep an even canopy works best with LEDs, but you can grow them straight too if you like, they just don't seem to get the size as under the older stuff. Here is another Jack Herer grown originally in a 2x2 under and SF-1000 light. Decent, but nothing super impressive imo.

    Heres how I figure when buying LEDs.

    #1 what size coverage area do I need, sounds like you are looking for 3x3ish

    #2 shop around, I tend to start with major brands (like Spider farmer, HLG, Mars hydro) then see if I can maybe get a better deal on something more off brand with similar specs (or get parts separate and self-assemble).

    #3 specs, so with LEDs idgaf about the watts it pulls from the wall (except for calculating load on the circuit), I care about the spectrum (which tbh most of the major lights are pretty close on imo), and the micromoles per second of light it puts out on the canopy (umol/s)

    #4 Seedlings can need as little as 100-200 umol, big ass photos in flower can take 1,000+ umol/sec (above 1,000 the diminishing returns kick in pretty sharp on adding more light unless you are also growing in a high CO2 atmosphere.)

    So once you have a light you think you need, check your grow space and figure how high you want to set your screen (or training, or just how tall you figure the plant will grow) you will need at least 12 inches above the plant to hang the light, plus another 6-8 inches above the light itself for heat dissapation.

    Then find the light at the best price that can get you at least 500 umol/s to all the edges without being super hot in the center (over 1,100-1,200)

    So something like that TS-1000 in a 3x3 might work (or anything comparable) Just google your light and PPFD map, get something like this.

    For me, the sweet spot on a light like this would be around 16 inches from the canopy. (at 12 inches the center may be too hot at 1,350 and torch those plants, and at 18 your sacrificing too much light in the second and third rings out from center imo. (or if you had room to position the plants mostly outside the center "hot spot" 12 inches could work, but that will depend on how many plants you want to cram in there.)

    Anyway mate, hope this alleviates some of your questions on LEDs, but they do work, and they are cheaper on the utilities, although they will only raise a grow area temp by a few degrees unlike the HPS which were almost a heat source on there own for grow spaces.

    Final note make sure you get a light with an intensity adjusting knob, sucks as the plants grow to not be able to increase light without re-measuring and hanging the light to the proper distance.

    Full spectrum LED's (whitish ones) have also done much better for me than the older "blurple" style LEDS as well.

    Apologies if you knew any or all of this already, but this has been my experience with LEDs for the last couple of years.
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  4. I'm in the north east, i usually grow in the winter and use mh and hps inside to take place of the heaters.
    Last year I grew in 10 gal cloth pots,outside in the summer and brought in barn for last 30 days. The hps finished them nicely.
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  5. The marketing for LEDs can be a bit misleading so the point that was made in the first response is very informative. I've got units throwing 150 watts in enclosures measuring 1.5 X 3 which are capable of handling extended veg
    or flowering.
    The same general concepts from HPS or MH hold true for placement - give things about 18 inches of headroom so that heat or intensity doesn't negatively impact growth. The trend has shifted towards full spectrum units as opposed to the early blurples or higher kelvin for MH (4000k plus) and lower for HPS (2000k plus). My main space is using two fixtures throwing a combines 600 watts (overkill) over a 2 X 4 ft closet. Not sure your personal style of growing but I lean heavily on very aggressive LST. At the very least, it promotes several competing main colas and on the extreme end an entire network of bobble heads. Pictured below is the main space showing the benefits of continuing manipulation; even though the mains display dominance, there is plenty of open space for the normal undergrowth to shine a bit brighter.
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  6. Thanks for a ton of info. That will keep me busy for a spell..
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  7. TY for that.
  8. #8 Vee, Feb 13, 2023
    Last edited: Feb 13, 2023
    of all here I'm gonna miss my basket ball light and the gym light
    but use in darkest winter to keep the room warm, heating the grow room
    as an extra cost, mine is 2x migrow 8's 16sqft of light in 15sqft
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