upgrading to led

Hey guys. I use a 600w lumatek digital ballast with cooltube and dual bulb for the time. In order to substitute it with leds (yield wise) how much watts leds would i have to use? After a lot of reading and the help from mombers from the forum i understand that the brand of the leds and its final make play a very important role. So i believe that from what i know now the replacement should have the cree cxa 3070 or higher and bridgelux vero 18 or 29. How many watts of these brands would i need to substitute my hps?
THanks a lot in advance

I really depends on how efficiently the emitters are driven. A rule of thumb is it takes about 65-75% as much led wattage to get the same result as hps. I suggest starting with ~400w. You can always add more.

Mike beat me to it, it would depend on the efficiency of the lamp you design, but with most modern warm white COBs, I would suggest at least half as much wattage. If you use 75% of the wattage you can expect a yield increase. I replaced (4) 600 HPS with 1250W of LED. My best HPS yield was .57gr/W, my best COB yield was 1.4gr/W.

However, my worst HPS yields were .3gr/W and my worst COB yield so far was 1.05gr/W. So no matter which way I cut it, my total yields increased even though my power usage decreased by half.

The heat decrease is a whole nother story. The 2400W HPS was creating at least 1560W of heat. The LED is creating at most 690W of heat.

SupraSPL said:

Mike beat me to it, it would depend on the efficiency of the lamp you design, but with most modern warm white COBs, I would suggest at least half as much wattage. If you use 75% of the wattage you can expect a yield increase. I replaced (4) 600 HPS with 1250W of LED. My best HPS yield was .57gr/W, my best COB yield was 1.4gr/W.

However, my worst HPS yields were .3gr/W and my worst COB yield so far was 1.05gr/W. So no matter which way I cut it, my total yields increased even though my power usage decreased by half.

The heat decrease is a whole nother story. The 2400W HPS was creating at least 1560W of heat. The LED is creating at most 690W of heat.

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Have you noticed that using LED's gives the bud a little more resin in comparison to the older lighting sources, such as HPS?

Yes definitely. My patients (and wife) definitely noticed and appreciated the switch from HPS to LED. My soil mixture has not changed and it is the exact same soil (literally reamended and reused) and water before and after. Many of the same cuttings run over and over. My theory is that the HPS "cooks" some of the flavor out of the terpenes and/or the increase in 450nm blue affects the trichs somehow. I ran my HPS bulbs bare but I did not let the canopy temps get above 82F. With LED the lights-on canopy temps are 75-80F.

I also got to sample a lot of the same cuttings grown under my friends big HPS setups and compare them under the LEDs.

Actually when I look back, I switched from LED to HPS and back to LED. That is because I started off very small closet style with a DIY LED setup back in 2009 and it worked much better than my 70W HPS. But when the time came to build a large system, I bought (4) cheapo 600W HPS setups from HTGSupply for $800. It did not seem practical to build that large of an LED. But once COBs came out, it was no problem at all to replace all those HPS Watts. I didn't even have to sit down at the soldering bench, just leaned over to make 4 connections and then hang the lamp.

Moral of the story though, when I switched from DIY closet LED to 600W HPS setup, the trichome and bud quality noticeably decreased. It was still good bud though so I went with it. But I am glad to be back to LED.

As a side note I have always used LED for vegging, phenomenal power savings compared to my friends metal halides and fluoros and it is more customizable to the shape of your vegging space. Mine is shaped like an L on the outsides of the tent.

thanks a lot guys!