I have a 3’ x 3’ x 69" tent. I bought LEDs in large part because they are not so hot. However, I have a 1000W HPS and was thinking about trying it, but it seems like it would be way to hot. Not only for overall heat, but the plants getting too close. Anybody have any experience that might be helpful?
If you can keep the heat down, you could scrog the plants to keep them from getting light burn. Some plants get taller than others too.
It should be an adjustable balist maybe turn it down a bit.
A cool tube and a centripetal force inline fan work for me with a 300w hps in a 32"-32"-53" inches. Tent. A little smaller. A bigger fan will be needed for a bigger light. I’m thinking 10 inch or 12 inch fan for a 800-1000 watt hps.
If it does work out your going to have a great harvest. Good luck
My tent is 4.75x4.75x6.75 and I have a 1000w HPS and it’s very challenging to keep the heat at bay. I bump it down to 600 for veg and they seem to love it 
Disclaimer: I’m a newbie so can’t answer your question exactly… but can share my experience 
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I’ve got a 400 watt HPS in a 32" by 32" by 8’ shower we never use. I flipped to 12/12 at 21" high and it stopped growing at 44". Between the 5 gallon bucket and light distance that’s good because I would have to redesign the light fixture to get it any higher. It’s done fine and is loaded with colas that are days away from harvest.
I suspect 600 watts would be overkill, as in burnt plants.
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If you get a air cooled hood and a good exhaust and you might pull it off with a lot of LST
I would put it in there and check to see if you have a dimmable ballast to see if you can turn down the wattage and give it a dry run for 2 full days on your light cycle you are wanting to use and record your hi and low temp that will tell you if it will work
Thank you all for your input. It does not have a ballast you can dim, it is actually almost 20 years old.
@Sismokes I think your idea is great, the only problem is that I don’t have the bulb. So, I would have to buy the bulb. If it doesn’t work I am out the cost of a bulb. It isn’t that much, but getting this set-up as adding-up. I posted this to determine if it was worth getting the bulb.
@bigfellan I have two 300W LEDs and likely could add a third. Each LED runs at an actual 135W. I have a read many times you want 50W per square foot. My tent is nine square feet, so that would be 450W. However, I have also read you need slightly less watts with LEDs. So, I think three should be just fine and two may work. BUT, it would be nice to just use one 1000w light.
@bigfella I forgot, congratulations on your upcoming harvest! Wish I could try it 
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Yeah, I wish it would hurry up: The suspense is killing me. Pistols have all been brown for a long time but the trichomes say it is not ready yet.
Re your LEDs: Your LED manufacturer is claiming their LED is equivalent to a 300 watt HPS. Two would be 600 watts HPS. I would try them and see if you really need more. I have a 400 watt HPS in my 32 x 32 grow closet and it’s doing fine.