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Hey psu how have you been? Paper/data days 75%+ I docked 5% for the uncertainty factor lol. Maybe I should dock another 5% for over optimism factor but I have yet to cough up the funds to have any tested in calibrated integrating sphere. I do have a lab not far away so I really have no excuses...

The performance of LED grow lights can vary by a huge amount. There are cheap LED lamps on the market as low as 20-25% efficient, quality commercial COB lights are 45-50% efficient, some DIY builds are 70% efficient. In my opinion the performance of a typical 400W HPS is equivalent to a high...

When I first attempted to graph the data from my PAR meter measurements I decided to use PPFD/W @ 12" for several reasons. The sensor method I used (Apogee PAR meter open air @ 12") measures PPFD (photons/area/second) rather than PPF (total photon output/second). In order to measure PPF you...

Yes I brew these 1 liter teas from time to time and I use a biological scope to check them out. It works very well even with an aquarium air pump. That is all an indoor grower needs when it comes to microbial tea. For nutrient tea we probably want a larger brew and larger air pump. The nice...

Yes that makes sense, the cheapo LEDs make a lot more heat than light LOL. I settled on 750 PPFD as a compromise for my ideal bud size and based this chart, adapted by @Rahz, I marked the area I settled on as a compromise between efficiency and yield/sq ft. Most growers would put more emphasis...

That is good info, I am up to about 30% now, not counting the DE. Maybe I will try going higher. Thanks for the link. I agree @hillbill that DE behaves like vermiculite, holding water. In theory a TDS test should be useless but in practice I find I can assess a soil's fertility pretty well...

What lights were you using before? 1260 PPFD is very high in the scheme of things, so the soil and roots would have to be very on point to keep up. I flower 3'-4' ladies at about 750 PPFD, but I have to lollipop them a bit to avoid larf when they are 4' tall.

I got a cheap NPK test kit and the results say that my spent soil still has surplus N, surplus P and adequate K. So I stopped watering in fish hydrolysate and started using more blackstrap molasses. I backed down the chicken manure in the recipe and increased kelp meal and greensand. PH was good...

After a few years I have had to cave in and add perlite to the mix. I noticed that the ladies in smaller pots were doing better than in the larger pots so aeration is suspect. The old perlite from the Roots organic soil has broken down and apparently the 8822 diatomaceous earth is holding too...

Hello COBkits, thank you again for all your hard work! I have a bunch of questions regarding the sphere tests if you have a minute, some I found the answers to in the earlier pages: -Do these figures need correction based on the chips SPD and the li-cor's curve, or is the curve flat enough...

Good info thank you for that hard work! Now I have to try this CXM22. I will also do a thermal test to see if that backs up my PAR measurements. I love this stuff so I hope you dont mind I have a bunch of questions, I will move over to the other thread though.

I have been running 5000K CXB3590s and no complaints. I agree with nogod, it is strain dependent. I tend to run lanky sativa doms and avoid bushy indica dom. When in doubt, go with whichever one you can get in a cutting edge bin. Maybe we can get some 4000K CXB3590 in DD at some point. Even with...

Interestingly, I saw Bridgelux made a negative comment about running COBs at low currents, they advise not to do it because results are unpredictable see document below. Maybe they are worried about variable color temp. To add insult to injury, they recommend dimming using PWM. PWM dimming means...

Hey Mark long time! I still owe you one for sending those monster sized COB samples :eyesmoke:

Regarding the accuracy of this chart, I used the PDF data and extended the droop curves as best I could. CREE has always been known to be top notch and hit their marks, going back to the days of CandlePowerForums flashlight modding so I do not doubt their capability. I do recognize that there...

I have been out of the loop a bit but I have worked up the numbers for the large Citizens and Samsung S6 boards, looking for something that might top the efficiency of the CREE CXB3590. So far I have not found it, but I am searching for it so please bring me up to speed if I am missing...

The CREE datasheets don't bother with data at low dissipation levels, I assume that is because CREE could not conceive that customers would use CXB3590s at 25W or less. I had problems getting reliable measurements at less than 4W/ COB @ 12", but I can confirm that efficiency continues to...

Yes, that highlights the reason COBs are reaching such high efficiency compared to single diodes, reducing current droop and to some extent temp droop. If you run a CXB3590 @ 25W, each die is running at only .15 watts yet $2.75/PAR W is still reasonable. If we ran an XTE at .15W, we would be at...