The Philips 315w CMH is the best bulb/ballast tech out there imo, quality/trichs and production wise. Penetration with either tech is a non-issue, both can build 30" buds with little popcorn. idk about the claims about higher potency but they grow top shelf bud. For the price/watt if I hadn't had the cash to invest in the COBs I'd still be running it. No problem recommending them if you're looking at them. Just be careful with ballast compatibility, if you can get a unit with the Philips ballast I'd recommend paying a little more as they know how to drive their own bulb. Have heard some knock off's not performing as well and they need specific ballasts to fire and run the bulb properly. Bulb life in the Sun Systems with the Philips ballast was ~ 1 1/2 years then started to drop off in production. The most prominent feature with this tech is it finishes anything you put under it about a week faster than any tech, must be something in their spectrum as this has been reported by many users.
The COBs, I have mostly Cree 3590's running at 1400ma and recently added some Citizen 90cri COBs that I'm just finishing the first round with and seem to perform as well or better than the 3590's. Looks like they finish the plants faster, have to validate next round with some known clones as my first run under them was 2x 5gal from seed. I just pulled a Panama reg sativa (pulled it last night, see pic below) that's said to take 11-13 weeks in 70 days under the Citi COBs. Production is about the same as CMH, maybe a little more, easy to get 1 gpw, even in pheno hunts from seed. I don't do commercial grows for weight, do a lot of breeding and pheno hunts, typically running 6-8 strains and average 1.1-1.3 gpw at 30w/sq./ft. What sold me on sticking with the COBs has been potency and terp production. I had a couple of phenos that I'd been running for a while and when I ran them under the COBs it was like running a whole new strain, the terps are through the roof strong in comparison to when I ran them under the CMH.
To your question on penetration with the COBs, this is the Panama (smaller of the two I ran) from seed I pulled last night at 10 weeks. The door is 36' wide, the door knob is 37" from the floor, it's in a 5 gal fabric pot.
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