LED lighting and deficiencies

Discussion in 'LED and other Lighting' started by DesertHydro, Apr 4, 2017.


    DesertHydro Well-Known Member

    my new grow is doing the same thing. one thing i had seen in another thread that may help is raising the temps? i saw that 85 is the suggested temp for LED since there is little heat downward and the plants dont transpire as much. since cal is mobile it is taken up as the plants transpire. this is going off of memory and i was super baked when i read it last night and cant find it again.

    Typed this yesterday but after checking my runoff ph tonight I think that's the culprit. The bulk loose rock wool is notoriously high in ph even after my 4.5 initial soak. Gonna feed at 5.4 for the next few days until my runoff levels off at 5.6-5.8
    That should clear this mess up once and for all. May need to build a doser to keep the ph in check. Jacks is stable as hell at 5.8 but it's no match for the alkalinity of the loose rockwool

    CobKits Well-Known Member Rollitup Advertiser

    rockwool is only alkaline because of the lime they mfr it with. once sufficiently flushed, its neutral

    try a soak>drain>soak cycle in 5.2 it works for me

    CobKits Well-Known Member Rollitup Advertiser

    and yes youre right plants need to transpire to take in calcium so you need to play with the environment a bit and it helps to understand VPD. if you can drop humidity you will transpire more as well

    DesertHydro Well-Known Member

    i soaked mine overnight in 4.5 ph water and the water read acceptable ph levels after the soak. i think next time i will prepare my media a couple days in advance and let it soak a few days. other than that the LEDs are kicking ass. i think i can lower them down as soon as i dial in this ph issue. i thought it may have been an intensity issue at first but seeing how the runoff ph is just out of the the calcium uptake range for hydro it all makes sense. i have raised my temps and my rh is right on par with the VPD chart. im in the mid to high 60s at all times.
    crocodile og

    crocodile og Active Member

    I've never soaked rockwool for longer than it takes to saturate it.

    I'll accept a pH of 5.2-5.9 and be happy with 5.6 considered perfect.

    Never had any issues using this method.
    OneHitDone likes this.

    CobKits Well-Known Member Rollitup Advertiser

    i used to soak overnight in 5.5 the pH of water would def go up after a day or two. now i soak/drain/soak in 5.2 and spend a minute on it, seems to be working
    OneHitDone likes this.
    crocodile og

    crocodile og Active Member

    Whats the runoff EC?

    If its too high you might have a potassium deficiency.


    Also a possible cause for Magnesium deficiency.

    Reasons for a deficiency
    The magnesium deficiency can occur because uptake is inhibited because of:

    • A very wet, cold and/or acidic root environment.
    • A high quantity of potassium, ammonia and/or calcium (for instance high concentrations of calcium carbonate in drinking water, or clay soils rich in calcium) in comparison with the quantity of magnesium.
    • A limited root system and heavy plant demands.
    • A high EC in the growing medium, which hinders evaporation.

    DesertHydro Well-Known Member

    I don't think it's any of those things. Drippers on timers and everything pretty much runs itself. Haven checked runoff ec but I will today. I water til runoff every day. Ph was 6.2 which is just outside of cal uptake in hydro. Couldn't find my ph down last night so I will fix it today.

    DesertHydro Well-Known Member

    Oh and I'm only running 1000ppm. Same as always from start to finish and never a problem.

    Rahz Well-Known Member Rollitup Advertiser

    I grew under cobs for about 3 years, plants were always healthy except for a few instances of root rot in the beginning when I was using a bunch of additives. I started checking PH every day. I almost always had to adjust, at least for the first 2-3 days in a weekly cycle. That was RDWC so results may vary.

    PSUAGRO. Well-Known Member

    Why are you checking runoff? It's not accurate at all or I'm missing something?
    Last edited: Jul 20, 2017
    OneHitDone likes this.
    crocodile og

    crocodile og Active Member

    If theres a salt build up in the medium then it will be shown as high EC in the runoff.
    bakedPotatoe likes this.

    OneHitDone Well-Known Member

    Where is this misinformation about calcium being available below 6.2 coming from? I keep seeing that posted on these forums so I guess it must be fact lol :P


    DesertHydro Well-Known Member

    that looks like the soil guidelines and im in hydro. ph chart.jpg

    DesertHydro Well-Known Member

    runoff was waaaaaaay high. I flushed with ph'd water until runoff was acceptable ec. I will start doing a weekly quarter strength flush and use the shop vac to suck up the waste flush water. set my ph to 5.5 as the runoff ph was still high. should level off after a few waterings.

    Mullumbimby Well-Known Member

    I just read this whole thread. As I moved through I kept thinking that this was not a problem that was going to be fixed with more or less of any particular additive, nutrient or mineral. I'm glad that you seem to have figured it out.
    I thought everyone had learned to water until there was fairly substantial runoff, to make absolutely sure that the entire rootball had been fully soaked with fresh nutrient solution, and that no permanent or semi-permanent dry zones had been allowed to form within the root mass.
    If you are using rockwool cubes, you should have a look at 'Cap'n Style'. I don't do it his way exactly, but I learned a heap from reading everything the Cap'n had to say about root health.
    Great thread (for me at least - I'm sorry that you've suffered) and, as I said, I'm glad to hear that you seem to have figured it out.
    crocodile og and DesertHydro like this.
    crocodile og

    crocodile og Active Member

    I think about 20% should be run off minimum.

    Too many people advocate 10%.

    If you monitor it week to week you can get a pretty good idea of how much your plants are consuming and tailor accordingly.

    If that was the problem you should see a positive reaction pretty quickly and no more progression of symptoms.

    CobKits Well-Known Member Rollitup Advertiser

    lockout is a bitch! messes everything up. glad youre back on the horse
    jacrispy and OneHitDone like this.

    CobKits Well-Known Member Rollitup Advertiser

    media moisture content is critical when running high ECs. not sure which ppm scale youre on but say it was 0.5 and thats 2.0EC, it doesnt take much transpiration for that media to get close to 3.0EC

    bakedPotatoe Active Member

    This is why ive come to love coco.......
    crocodile og likes this.

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