That's probably your problem right there. Too much light is also bad for the plants.
I kept the light intensity the same when replacing my 1000W HPS DE with COBs. With the 1000W DE HPS I would get on average 1250g per light (boosted to 1150W). So say about 1.1g/W. WIth COBS I went to 1,4g/W and that was old 2.0umol/W COBs.
I should clarify a few things here.
Pretty sure everyone and their grandma is getting about 3lbs a light at 1150, including myself with solid genetics.
I did not have too much light. I own a PAR meter and a spectrometer.
I made sure I was running 900-1000 PPFD at the canopy. My plants were very healthy.
Same genetics 2 runs, in The second run I lowered the PPFD to 700-800 PPFD.
I didnt not see much yield variance between 700 and 1000ppfd with COBS.
I have run many tests with Veros and Citi LED in smaller conditions.
Here is my yield for my first run. Will find data for second run.
DE Run 1 :1723 Grams ( top quality, probably a few oz of larf for edibles, never weighed that part) = 1.49 Grams a watt
1000w CXB3590 Run 1 : 1451 Grams = 1.26 Grams per watt if you like to gauge things this way.
I am in no way saying COBS dont work. They provide an excellent yield. I would still love to play with some higher K spectra and some UV with COB lights and then I will likely see a high yield, but for now these are my results.
Also to answer a question i know someone will ask. I run some very high yielding strains. One of which being my own. Yield comes down to genetics, light spectrum and health.
COBS are fantastic, I should have clarified that better. They do work very well. However I still see far better results with DE HPS.
Plus in Canada Buying or building a COB fixture is just very expensive and electric is fairly cheap. DE fixtures are cheap. AC is cheap and for me I just run an intake and outake and a wall fan and get good temps rh and VPD.
I will be pl;aying with some COB spectra again after this DE bulb run to finally answer the question. Which K temps provide the best growth in each stage.
To any hobby growers, yes COBS are worth it, are they worth the money? Depends on a few factors, such as heat and your budget. yes you can run a DE at 1150 in a 5 x 5 wtih temps well under 30 with an intake and outake of 400cfm each and a wall fan/ box fan.
I hope this gives a bit more insight. LED is the future, just not yet in terms of price and yield from my runs with my genetics.
Here is some bud porn of my own person strain: Cocolate Covered Creamsicle Dough
Genetics of this are:
Sin Mint Cookies x 24k Gold = Gold Cookies
Gold Cookies x Purple Glue ( GDP x Strawberry Glue) = Glueberry Coast
Glueberry Coast x 5 Little Ducks ( Frisian Duck x Critical 2.0) = Chocolate Covered Creamsicle Dough or CCCD
Enjoy, Trippy