Only change to LED from HPS if your going to buy quality. Cheap ones are not cooler than HPS.
Be very careful what you buy, if a light is advertised as a 600w light but only has 200w of power then that's a sign they are selling a load of lies.
The way forward would be as suggested cobs or quantum boards, they are good because they are vey efficient, so you really can run 250w and cover a 4x4 and have more light than a 400w HPS. All these cheap lights on ebay/amazon are cheap for a reason.
If your going to do it buy from a know advertiser on here. There are a lot of Chinese manufacturers jumped on the cob band wagon churning out crap.
Sound advice.
It's ask not all about the wattage I'm my honest opinion.
My light gives my plants more PAR light than they can absorb - don't need more for a 5x5 tent doing SCROG.
Here is my light I got built:
My light is custom made, here is information:
12 Cob Vero 29 D series SE
1400 PPFD at 8"
6 COBs BXRC-40E10K0-D-73-SE
6 COBs BXRC-30E10K0-D-73-SE
108,000 lumens
Switchable 6 COBs on veg/12 COBs on flower
230w per rail
690 w total.
Picture attached showing 2 of 3 arrays on but only the 6cobs for veg.
It comes with a dimmer switch per array 1-12 dial and I can add a ton More COBs if I wanted to this array.
My third array was damaged being shipped and should be back tomorrow!!
It's worth the investment especially in Ontario where Hydro is super expensive as I'm able to turn off 6 COBs not being used in veg.
I would stay away fe
Blurples etc as they aren't as effective and if something goes on it the whole unit goes.
My light wasn't cheap tho but very happy with my investment especially since my plants are important and light is important to them.
Hope that helps - I'm new but would prefer to buy an item that's top notch and upgradable as well as great for electricity and not over kill