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I built a 250W Cob LED painel, but it's dimmed to operate at 170W. My grow space is 0.42m2, light is providing 800 PPFD, more than that can stress the plants so I prefer to play safe. The soil is a mix of decent potting soil, German brand, don't remember the name, plus 30%-40% perlite and coco...

Pots are 3 gallons size. I have been watering half a gallon each plant every 5 days, I know when I need to water by checking the pot weight and humidity on the soil surface. I'm growing with LEDs, so less evaporation due less heat. Soil has a nice amount of coco and perlite (30%-40% or so) for...

I'm growing in soil. I'm not expecting to get rid of the problem in one day but the deficiency is progressing very fast, I need to take action to stop the progression but I'm not sure what it is.

Hey, My plants are flowering for 3 weeks and in the last week I noticed some leafs turning pale green, then yellowing in the bottom and middle of the plant, doesn't look like nitrogen problem. I guess it's a cal/mag issue so I watered with Epson salts yesterday, so far no recovery. I need to...

Is the first graph representative of absolute output? If so, I suppose the testing was done with the same current across all chips. If my understanding is correct, at first glance the 5000K seems the most efficient. The 3rd graph shows relative intensity. What exactly is that? Sorry if I'm...

The discussion is interesting, would be a shame to it let it die for ego reasons. It would be nice to read some explanation on how normalization affects the reading of the graphs. Thanks!

All curves in the graph are given for TJ 85ºC, at 1620mA, so I guess you can compare them objectively. Edit: But I will admit my first thought as the same. Then I noticed this "TJ 85ºC, at 1620mA" on top right of each graph.

Not so sure if it isn't significant. Having in mind the pictures I wouldn't be surprise if the 90 CRI yielded 30% more or so. That would be enough to justify the upgrade, the new COBs would be paid off in a single grow. Before any conclusion/change I will wait for the final weights.

Would love to know the final weights. I wonder if someone else did a side by side comparison like Dawg is doing here. Not saying this experience isn't reliable but would be good to have more sources of comparison before a definitive conclusion. Now I feel frustrated to have chosen 4000k...

That's great info. Based on that graph, assuming we are using COBs, I would say above 600 PPFD one would need to spend around 60% more energy to get 25% more yield. Not counting the risk of something going wrong when growing conditions are pushed that hard.

Running 73F at soil level, 78F at canopy level, no extra CO2. You are right, photosynthesis is optimal at higher temperatures, which I don't have. Just dimmed my lights from 250W to 170W (1260 PPFD to 860 PPFD). Took to long to fix the problem, at 4th week, bud formation is already...

Considering the thread "tomate" posted, it seems many COB users had to increase cal/mag feed in order to the keep up with the higher PPFD. I used mainly cheap LED lights before, my bet is the PPFD was much inferior. My plants are 2' tall in 3 gallon pots, so I would say they aren't the most...

Dear growers, I'm currently running my first grow with COBs. I noticed the appearance of deficiencies that I didn't had before, Magnesium being the most noticeable. I have been struggling to fix it, first checked my pH, seemed a bit low, added some dolomite. Later, added some epson salts...

Seems OK. Check drainage on your pots as well. Post some pics of the symptoms if you can.

Check your pH and all environmental factors (heat?!) in your grow space. Use decent potting soil with perlite. Some potting soil have the pH too acid, check that. Unless you have used the same soil a few times in past grows, I doubt you will need to add cal-mag or Epsom salts. It's unlikely the...

I don't think you will ever experience that problem. I apply 2-3ml/L and never had any nitrogen deficiency symptoms. If that happens to you, you can feed more heavily, but rule of thumb is go easy and don't feed more than needed. Go gentle, if you see bottom leaves yellowing you might need to...

My growing space is 4.5 sq ft, I'm using 5x 1212 driven at 1.4A. That gives 55W per sq ft. Initially I had some problems since the plants weren't big enough to handle it, after a few weeks my plants now seem to handle that amount happily, distance 10"-12". Once I realized my plants couldn't...

That will work. Don't be too worried since it's hard to overfeed with those nutes. I cut the bio grow (I use fish mix) on the 6th week. Be sure to provide enough nitrogen during the first weeks of flowering and the oposite applies on the end of flowering, too much nitrogen by the end affect buds...

Hey. Amazing grow. It seems plants tripled in size when you flipped, insane. How far from the cobs are the tops? Any light bleeching issues? Have you been running the cobs at 300W from the beggining or you dimmed the lights at some point? Very impressive for a first grow, you will probably reach...

Hey, very nice plant. What happened to the clones? Couldn't handle the light? Are those Citizen 048 2700K or 3000K? How about the CRI? The stretch was massive, hard to believe is the same plant, how far are those tops from the COBs? No light bleeching signs? It seems the plant is doing fine...