Leaf Bleaching: Too Much Light?

Discussion in 'Sick Plants and Problems' started by CasualObserver, May 25, 2013.

  1. Hey Grasscity!
    This isn't so much a question as an informative post for future Googlers. Discussion and your experiences may help someone, so speak up!
    I've had leaf bleaching problems in the past so I wasn't totally freaked to see what I thought was it beginning the other day, almost a week into flower.  It seemed to be affecting primarily the larger leaves with the most direct light, but seemed only to be the bottom 2/3 of the plants. The 1000w HPS was about 30" from the canopy. I haven't had bleaching issues in some time, but there are differences for this run than those previous.
    This cycle is in a new location.  An unfinished bedroom while my primary space is torn out and rebuilt to better accommodate the oppressive summer heat we get around here. Other differences: Using a old Diamond magnetic switchable ballast, an open reflector (vs. air cooled tube), and I used about half and half RO water and tap water.
    My tap water is crazy hard running between 600 and 800 ppm.  Honestly.  My RO system which badly needs new filters is producing about 150 ppm "clean" water.  Considering "hard" water starts around 160, I believe, that's still kind of high, but it's definitely better. I Googled "leaf bleaching" because I didn't think my light was close enough to cause a problem and it passed the back of the hand test. I found some non-alternative gardening sites that talked about plants being under-fed having bleaching problems.  When I first made up my rez water, I made it to spec using the Lucas formula. Because I used half tap water, my meter wouldn't even read how high the TDS ppms were (over 2,000). I had removed a third of the water and replaced it with clean RO water, bringing it down to ~1,600, but lacking the full punch of the Lucas formula.
    I changed the rez to all clean RO water and dosed according to Lucas (rez at normal levels ~1150ppm), raised the light as high as I could get it and the bleaching has stopped, new growth looks good.
    There are a number of parameters not being discussed, but this post is wordy enough! The moral of this story is: Bleaching is not always strictly a "your light is too close" problem.  In this instance, the light was probably fine at 30" had the nutrient soup been made with clean RO water to begin with. Using tap water increased ppms to unmeasurable levels and the  pH to just outside preferred levels. When ppms were corrected (somewhat), it left the plants under nourished and susceptible to bleaching, although the hard water kept TDS readings high (1600). The fix came with a complete rez change using all RO water.
    Pics taken today, flower started on Mother's Day (13 days), issue first noticed about a week into flower.
    View attachment 1210628
    Raising the light was the first thing done. It's been a couple days since the rez change and they're doing well, I may just leave it.  The remaining pictures are of the symptoms, which have stopped worsening. New growth looks good.
    View attachment 1210630
    View attachment 1210629
    View attachment 1210627

  2. Criminy! The pictures are enormous! Sorry!! 
    And the one close up doesn't really look as much like bleaching to me as some other deficiency....but again, crazy hard water and elevated pH are probably locking out the nutrients that are there. So regardless, use good water!
  3. Do this, and make sure your ph is sorted. That's not looking like bleaching, especially if its on the lower part of the plant.

    Getting your water and ph sorted out will actually recover your plant. (It looks like a mobile nute def. like nitrogen)
  4. I second the N deficiency. get quality h2o, ph balanced and update.
  5. #5 ndavisenterprise, May 25, 2013
    Last edited by a moderator: May 25, 2013
    My friend, I grow one plant monster cropped (tipped, topped, LST'd, super cropped, trimmed up,) and then SCROGGED out! You can produce over a lb off one plant. Keeps you under legal limits (for me, 4 in flower), only one plant to tend to and baby. Problems are a lot less!!!!

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