What to believe, digital Ph meter or strips?

Discussion in 'Hydroponic Growing' started by Tommatt, Jul 29, 2010.

  1. Ok, so I got a new Ph Meter Amazon.com: HM Digital Meters Waterproof pH/Temperature Meter: Health & Personal Care, and I used it in my DWC resevoir. I read about 6.06 or so. Took a sample from the bottom. It read 6.07 or so also on the digital meter.

    On my PH strips, its reading closer to 5.0 Very orange, some yellow that turns into a slight green. Its looking like 5.0

    I tried 3 strips, one soaking for 15 seconds, one just dunk in and out then sat for 15 seconds, one in for 3 out for 12. They were all around the 5 range.

    But the Ph meter says 6.1

    I'm going out of town in about 12 hours for 4 days....
    I just put in brand new nutes and brand new water 24 hours ago. Been slowly adjustming my nutrient level while having a gallon of water with the right amount just slowly to keep it up. Although if it drops below its no big deal, total water level is another issue. 4 days, it'll get looked at on day 2 or 3 by someone, 6 gallons kept in 21 gallon tank.

    Sorry for posting in 2 sections, hydro and absolute beginners, but I need people to see this to try to see on which one to go on.
     

  2. Has the new ph meter been calibrated? If so, I'd go with what the meter says. But, that's me ;)

    Good luck! have a safe trip.
     
  3. what ^^^^^^^ YODA^^^^^^^ says. a calibrated meter is so much more accurate.
     
  4. Turns out the factory calibration was right. Used their 7.0 solution for calibrating, meter read a perfect 7.0 with the factory calibration. I wonder if the problem with my plants is for some reason my strips arn't reading correctly. I used them for about 4 weeks of veg :/
     

  5. Did you use the 4 calibration solution as well?
    It's best to use both calibration points to ensure accuracy, IMO.

    It could be that the strips aren't reading correctly, I'm not too familiar with them tho. I've only had experience with the ph drop test kit, and ph pens.

    If the ph strips are NOT reading accurately, that could definitely lead to problems with your grow :( PH too high / too low can cause lock out / deficiencies of vital nutes, etc.... On a good note, MJ plants are pretty resilient :) We can help you make them happy again :smoke:
     
  6. I don't believe it came with a 4.0 solution. Theres a beaker for the stuff thats there to keep it moist I guess. There was one pouch of solution for 7.0, although the manual says calibration is possible at 4.0, 7.0, and 10.0
     
  7. This is a single point calib meter.
    An yes - your pH bulb needs be kept in a storage solution.

    Even thought you have a single point calibration you should probably check against pH 4.01 so you know how far you are off.

    For your original question: is the meter more accurate than the strips...
    The meter is a digital device and given accurate calibration it will be spot on +/- meter accuracy. Strips are analog and rely on you comparing to standard colors. The standard jingo is "Digital tells you what it is and Analog tells you what it aint"
     
  8. I swear by my meter. I've tried the strips, i could never figure out what the PH was. The two colors never matched up with anything on the color chart. LOL

    I say if you calibrated your meter with the correct solution as you have, then you should trust it's reading.

    If you are already doubting a calibrated meter, you may as well pack it up in it's box and send it to me (nice meter ;)), and go back to using strips. :D.
     
  9. Heres why I'm having a hard time trusting it. I leave for work and my PH is around 4.4. I know it'll rise naturally so I leave it alone. I get home just now about 10 hours later, and the PH is at 7.14 or so! The water is just over 24 hours old, the nutes, etc... I added a tiny ammount of PH down to my initial water I was adding to get it down in the 5's. I normally sit around 6 with fresh water.

    And, of course, my strips say its a perfect 5.75 right now or so.... (No higher than 6)

    I'm going to end up killing these plants. They're ready to flower to as soon as I seal the room off friday :(
     
  10. ok mix your self up some water. nutriants in it and all the stuff you would add in your resivour, then test it. now leave it at the ph you have do not adjust it. let it sit. then measure it some time later. like you would in your resivour. see if it fluxs at all. then adjust your ph to around 6.3-6.5 and test it. then let it set for the same amount of time. start to eliminate factors. figure out what it is. i would trust the meater over the strips but nothing can top a good gh test liquid. it only cost like 4.50 here and its never wrong. but they are right that you should calibrate at 4.0 and 7.0
     
  11. #11 dirt no more, Aug 8, 2010
    Last edited by a moderator: Aug 8, 2010
    do a double
     

  12. you me by gh test liquid the little Green Bottle?
     
  13. Saw this got bumped up. I bought some calibration solution (both 4.0 and 7.0 and go entirely by the digital meter. My first cal, the meter was dead on. The strips were reading 1.0 higher, or I was reading them wrong. I wonder how many of my nut defeciencies during veg was to deal with this.

    Totally swapped nutes, using digital pen, have first clones going and a new seedling. Expect this to go great.

    Digital meter = Well worth the money

    (I am using Hanna PH calibration solution)
     
  14. hope no one minds me chiming in here, but does anyone ever have problems keeping the pH high enough? i'm in the middle of my first grow, about 1 and a half weeks into flower, still using veg nutes in the same amounts. prior to this, i would adjust the pH and it would steadily rise over the course of the day. now it's just staying low, and i'm constantly adjusting it. i use liquid test solution, GH flora series nutes GH pH up/down. the plants are still growing, pretty fast actually, but there is some yellowing on the leaves, mostly the older ones. this happened last week as well, and an experienced grower told me to flush the solution and start over. i did, and it worked great at first, but now i'm back to the same song and dance. is it ever normal for the pH to go down instead of up?
     
  15. I'm using the pH drops and vial thing. It works for me
     
  16. Yeah thats the same method i use. Its worked so far but i will probably end up getting a PH pen. I just got a PPM pen and its really nice. I would love the same easy of use and speed in a PH pen as i have with my PPM pen.
     

  17. I'm probably going to do another hydro grow. And I will buy the digital meter, it's kind of a pain in the ass testing the pH
     
  18. #18 blindbudsmoker, Oct 26, 2010
    Last edited by a moderator: Oct 26, 2010



    not sure how to explain this but this is not always right. i have the milwalke tri meter and tested it every few weeks and it always said 7 on the calibration fluid but then was still having problems so grabbed a couple more pens and the both read that the milwalke was high by a point. i always go back to paper or grabb more pens when i doubt.

    and as far the pens always buy 2, from what ive learned is that most are junk and u cant get the same reading off of 2. so take it off two and get a average. over time u will start to get a stock pile of them. i have atleast 10 broken ones in storage. the ones i liked the most are the worst ones ive used yet but the long blue stick ones, forget the company but have atleast 6-7 of those, all broke.
     
  19. I hate those handheld pH meters... they're as reliable as a crackhead. From now on I'm just going to stick to pH strips.
     
  20. Ya know what they say ...
    Ya gets whats ya pays for...

    I swear by mine and would not go without it.
     

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