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PH crashes on my hydro since going to flower

Discussion in 'Hydroponic Growing' started by Atari2600, Sep 14, 2021.

  1. First hydro grow and about 3 weeks since flipping 12/12. Water consumption averages 1.5 gallons a day and the plants are lush and healthy. I can honestly say this hydro experience is awesome so far!

    However, beginning over the last 2~3 weeks my Ph keeps plunging over a 12-18 hour period. My RO water runs 7, mixed with the general hydroponics flora series has resulted in 5.5 right on the nose until going to flower. I can check it at 5am and it is at 4.40, I top off the res and put in some Ph UP and it goes to 5.70 after circulating. At 10pm it is at 4.38.

    No adverse effects so far, growth is excellent and I am not freaking out, but is this a normal hydo behavior? Is there a best practice to deal with it?
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  2. too much phosphorous crashes the soup
    = phosphoric acid.
    what is your ec at??

    alternatively, you could add some calcium carbonate to your reservoir, just not too much, maybe even have to add a touch of epsom.
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  3. 1.82 if the meter is right.

    I have been draining about 2/3 of the water each week, refilling and then adding that week's nutes. Of the various suggestions on how to change and nute schedules and what not I had to choose one so I did it this way. Is there a method that is less susceptible to PH drops?
  4. I would change out the entire solution each week to ten days if the solution was unstable.
    could also be the nutes you are using... see attached.

    also, this diagram is helpful.

    Attached Files:

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  5. I'd worry about microbes.
    I use Clorox daily to keep them away, 2 drops per gallon every day.
    If something smells off, I double the dose.

    Another thing to consider is over feeding.
    If ppm falls from day to day, then plants want more food.
    If ppm rises, they want less.
    Over feeding can mess with pH.
  6. How many plants and how many gallons of nutrients does your system hold? Are you using bacteria to combat pythium? Can you send a picture of your root system too, at least one plants roots.

    Are you sterile or live? Do you use Microbes or Chemicals to combat the root fungus?
  7. Thank you all. I have 4 plants in a 4 station 1 res RDWC system that has roughly 22 gallons. Root temps are 67F, they all look like white cooked spaghetti with no sign of trouble. I am not introducing any bacteria, bleach or anything other than the nutes and PH UP as needed recently. I am using the General Hydroponics Flora series per the label feeding.

    It all looks perfectly healthy. I have been tracking PH but not EC so I will start to make note of that. I will have to get pics when I return home next week.

    And somebody please explain EC to me and how it works, I was NOT a chemistry major.
  8. Ppm is parts per million. How much stuff is in your water. For example ro water is 0 ppm, tap water is around 250ppm, tap filtered water is around 200.

    If you give your plants 300ppm and the next day it's at 290ppm that means they are eating more food than water, which is what you want. If it rose from 300 to 310 over a day then it's leaving nutrients in the res and drinking just the water, making your solution become stronger over time. This is over feeding and where most hydro problems come from.

    I use 10 gallon per plant in flower, so if you double your res size next grow, your swings won't be nothing. Larger res means less swings.

    Hoped this helped.

    I feed my plants no more than 400 ppm ever.. They love it.
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  9. EC stands for Electrical Conductivity.
    Some materials like table salt dissolved in water will cause the solution to conduct electricity.
    Up to a point the more salt dissolved, the better the solution will conduct electricity.
    Our water soluble fertilizer acts the same way, the more fertilizer dissolved, the better the fertilizer solution conducts.
    pH meters are really just electrical meters that measure electrical conductivity.
    Unfortunately these meters can't tell us what elements are present, just overall amounts.
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  10. Ppm meters he means :)
  11. I like to use EC meters over TDS meters because they are static, meaning the industry doesn't change the way they measure, whereas TDS meters can differ in the way they convert EC readings. Some convert by 0.5, other by 0.7, and then there are still way more conversions out there. But EC meters, all the same. What I mean to say is that one persons 400ppm maybe 550 to someone else using a different meter, but EC would be (example) 800, no matter what meter is reading (unless its uncalibrated or broken).
    is that 400 ppm using 0.5 or 0.7 conversion. See what I mean?
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  12. Only been growing since Feb, Ill get around to ec.

    But I don't know anyone that uses .5 scale, most normally use .7
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  13. Knowing EC and pH are extremely important in hydro.
    You should know reservoir EC before putting plants into hydro.

    I prefer the 5 scale because multiplying/dividing by 5 is easier than with 7.
    • Agree Agree x 1
  14. I meant I use ppms conversion not ec, one day I'll switch. Lol there's no way I could grow without using an ec or ppm meter.
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  15. u see what I'm saying right? I am at ~1.5 mS; this number doesn't change. All the other numbers are based on EC.

    There is also a newer method for measuring NPK, but not a cheap way to do it in hydro, other than using colorimetric assays, which is just a pita. I saw one commercial unit for real time NPK measurement (at the res) but I don't have that kind of money.
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  16. That was drinking from a firehose but I got all that, another piece of hydro made clearer!

    Now, after chasing phantom microbes and all sorts of things that weren't the problem I found the problem. I missed that my circulation pump was dead. I installed a flow indicator and now I get an alarm if the thing is off. But man that was just something I did not consider to even check. The plants had a few signs of impact; a few wilted leaves, a few lost fan leaves, and the farthest one in the circulation path was hit the hardest. Naturally they were in early-mid flower so there may be an impact to yield but they seem to be bouncing back and I consider it a lesson in my checklist for hydro troubleshooting.
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