Recent content by Delps8

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    Is this light bleaching?

    That couple be the early stages of "interveinal chlorosis" which is a symptom of magesium deficiency. On the other hand, it looks an awful lot like my plants do and it's just the "helicopter plant daddy" mode that I get into. It's very common for new growth to have that color and your plants...
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    Flower light question.

    "good" - it depends on what you mean by "good" and that's an entirely different topic. I was addressing your claim about HPS and provided the document as evidence that research shows that LED's have been shown to grow cannabis at 1800µmol. If you've got a link to the study, please post it...
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    Flower light question.

    I did not specify the number I was referring to and I should have. The number I was referring to was 2383 and I made the assumption that was the number in question. The idea never occurred to me that there would be any issue with 813µmols. My apologies for being unclear.
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    RDWC pump gph help

    I'm in hydro but it's one res that holds 26 gallons so it could be different. Have you checked out the setups at PA Hydro? If your design is similar to one of theirs, that could get you a good idea of what to use.
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    Flower light question.

    Using LED's researchers have demonstrated that cannabis will grow in ambient CO2 at 1800µmol. Amazing to think that HPS can go even higher. Could you post a link to the research?
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    Flower light question.

    That's great to hear. I know that's not the case in the US. Well, according to the DLI maps for the US, that's not the case. Below is a DLI map of CONUS from this site. An interesting pattern appears to be that, the further north you go, the lower the DLI. That may change once we get north of...
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    Day 52 Autoflower

    Looking really nice. Congrats. Check your grow against this graphic. Temp + RH = VPD. 1.0 in veg and 1.2 - 1.3 in flower. Good info on VPD here. How much can you control/influence temp and RH? Light? Get a light meter ($32). Once your grow environment is dress right dress, you'll be able...
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    Flower light question.

    Amen to the CO2. Per Bugbee, you get a boost in yield without even increasing the PPFD. The number that I've seen if you bump CO2 and light is 25% to 30% increase in yield.
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    Flower light question.

    PPFD at noon can hit 2300±µmol but that's only for a limited number of days, at certain latitudes, if the weather is good. Over the course of a growing season, PPFD/DLI is much lower. Why the 1k level? That's pretty much the max sustained level that cannabis can tolerate in ambient CO2. The...
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    Help me decide on a LED!

    Enough, yes. Optimal - only for the 4 sq ft in the center. Once you go past that, you (probably) won't have enough light to get to 800-1000µmol but, if you actually use the light to its fullest potential, you'll get a really good crop.
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    Lengthen flower period??

    No. Bugbee was asked this in a recent interview. There's no basis in plant biology to do that and, as he is wont to say, "we don't have any research that supports that." Light is food to a plant so when you reduce light levels, your plant is not able to make as much glucose and all processes in...
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    Seedlings reaching for the sky....

    No. Best small light on the market - I've got the prior model and it was a decent light. The new model is superb. Your plants are stretching because they're not getting enough light. In your situation, your plants should get light 18/6 (18 hours on, 6 off). If they don't get adequate light...
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    What would you pick led or hps?

    We don't make grow lights that mimic the sun because there's no evidence that plants use light outside of the range of 400 to 730nm. That's why it's called photosynthetically active radiation. Words like "better" is undefined so the discussion can turn into a fight over what "better" means. :-(...
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    What would you pick led or hps?

    We know the impact of different spectra. Blue photons make plants short, compact, thick stems, lots of small leaves, and short internodal space . Red light is used because it's highly efficient, in terms of photons per watt. That information is freely available and there's no mystery to it...
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    What light to use for 4x2

    My grow is in a 2' x 4' tent and I bought the SP 3000 when I started growing in 2021. The PPFD map on the SP 3000 is better and the spectrum in the SP 3000 has less blue and more red. Blue light tends to make plants short and compact, red light is far more efficient so you'll get more photons on...
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