Testing pH- can I just use pH strips or do I need a digital setup?

Discussion in 'General Discussion' started by SU2, Jan 11, 2018.

  1. SU2

    SU2 Chumono

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    Location:
    FL Gulf Coast 9a/9b
    I'm pretty ignorant re pH and realized how dumb that is considering the time I spend on learning & using micronutrients and stuff (ie I couldn't tell you my pH's but have a detailed mineral/fertilizer log), so was about to order something to test my water's pH and my substrate run-off's pH, but I'm seeing everything from super-cheap packs of pH strips to digital probing devices - hoping for suggestions on what to do here! Would also be very happy for any url's to information along the lines of 'dummies guide'/'intro to' pH stuff with respect to plants!!
    Thanks :)
     
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  3. When I managed a Quality Control lab for a chemical manufacturer, my lab had to submit to quality audits by regulatory agencies, because we supplied products used by nuclear power plants, I had to verify accuracy of our pH meters. Trust me, you will need at least a $2000 to $4000 usd unit to get anything that is ''accurate'', and you will need about 40 hours of training on how to standardize correctly such a beast in order to show precision. Key is both precision adn accuracy. pH is a really complex topic, and one could get lost down the rabbit hole worrying about pH. And except in fairly rare, specific horticultural situations, pH is trivial. Nothing to worry about. If you use pH paper, metters that are less than $2000 each, and if you don't invest in several hundred dollars worth of standard buffer solutions to calibrate the set up, you won't be any more accurate than consulting tarot cards. Throwing dice is much more accurate at predicting pH than any cheap pH pen type meter.

    Actually pH paper, will often give vague results, (meaning less precise) but is more ''accurate'' than any of the cheaper pH meters. If you have to check pH, use pH papers, they are the cheapest entry into the quagmire, and will actually give you a result with some, though limited accuracy. pH meters will display many digits past the decimal point, but they are truly not very accurate, and precision is an illusion. There is a long discussion we could do about the difference between accuracy and precision, but just contemplate it, we won't go there.

    Reality is, many, many, many bonsai artists turn out fine trees and have no clue what pH really means. My suggestion is to relax and forget about it. If your leaves are not showing signs of nutrient deficiencies, your conditions are ''close enough''. Remember there is such a thing as a useful approximation.

    More important than pH is a measure call Total Alkalinity, usually expressed as ppm of Calcium Carbonate or as mg/l calcium carbonate. Search ''Total Alkalinity'' on BNut, and you will likely find one of my multiple page mini-books on the subject. Get back to me if you can find an answer, or have further questions. PM or by tagging me in a post ''@''.
     
  4. Gustavo Martins

    Gustavo Martins Shohin

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    Location:
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    Second what Leo said. Cheap pH strips are crap. Neither accurate or precise. (I do know the difference).
     
  5. cbroad

    cbroad Chumono

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    559
    Location:
    Richmond, VA
    @SU2
    Why not look at an EC or TDS meter to test for available nutrients? I feel like that is more important than pH for our needs in bonsai. But like Leo said, it may be another situation where the only real worth is with lab quality products and not some $100 meter us civilians could afford...
     
  6. my main point was "you really don't need to worry about pH'' so don't bother testing.

    But if you must test - pH papers cost the least, and will give you better results than a $100 meter. The meter will give you an easy to read result, but that result will be meaningless unless you are familiar with how to properly calibrate a pH meter. That is a 20 to 40 hour discussion. pH paper will give you results that you can use.

    If your leaves are not showing obvious nutrient deficiency symptoms, you don't need to worry about pH.

    Even if you have nutrient deficiency symptoms, the solution is likely nothing to do with pH.

    pH is a "Red Herring'.
     
  7. cbroad

    cbroad Chumono

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    559
    Location:
    Richmond, VA
    Also, I don't know how testing the soil or runoff for nutrients with one of those meters would or could work... And if it was possible, the results probably would be completely inaccurate/useless. I just feel like knowing the amount of the nutrients would be more beneficial in bonsai.
     

  8. EC & TDS meters work by measuring electrical conductivity, no actual chemical information. Many different salts beyond just nitrates and phosphates will contribute to electrical conductivity. You really need to know a lot more about your water, and your fertilizer, before you can extrapolate an EC into a fertilizer or nutrient concentration. There is background work to do before EC data is meaningful. Once you know what the EC of water straight from the tap is, and the EC of your ''standard'' fertilizer solution is, then you can create a calibration curve so that you can convert an EC measured to an approximation of fertilizer concentration.

    More work than I would like to do. But I'm lazy.

    I measure the amount of fertilizer I use, by the volume as teaspoons (roughly 5 ml in volume). and I measure this into a fixed volume of water. My set up I fill a 55 gallon barrel with water, mix up the fertilizer. Then water the collection using a pump to push this water through the garden hose.)

    This way I control my fertilizer concentration and don't have to use any meters to know my fertilizer concentration.

    For my preferred 12-1-2 fertilizer with Ca++, Mg++ and micronutrients I know that

    1/4 teaspoon per gallon = 40 ppm as N

    1/2 teaspoon per gallon = 79 ppm as N

    1 teaspoon per gallon = 158 ppm as N

    I choose dose based on season and how rapidly or slowly trees are growing at the time.

    Useful link
    Fertilizer calculator - this is how I got the ppm as N per teaspoon.
    http://firstrays.com/free-informati...ion-of-fertilizers/fertilizer-tds-calculator/

    Really useful references put together with Orchids in mind, BUT remember, trees, vegetable crops and orchids need all the same nutrients in roughly the same ratios. Fertilizer information is pretty much applicable to all species of vascular plants.
    Orchids are grown in synthetic substrates - often bark chunks
    Bonsai are grown in synthetic substrates - usually a pumice based potting mix.
    Trust me, orchid nutrition and bonsai nutrition have much in common.
    Many articles in the link below, please dive in and read as time permits.
    http://firstrays.com/free-information/feeding-and-watering/
     
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  9. ysrgrathe

    ysrgrathe Mame

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    Location:
    PA
    You can get liquid test kits for fish keeping that measure pH, GH and KH. IIRC they are more accurate than test strips. But i agree really this doesn't matter unless you have extreme conditions.
     
  10. cbroad

    cbroad Chumono

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    Location:
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    @Leo in N E Illinois
    Good info, thank you for that. Haha I knew that figuring out the nutrient concentration would be way more complicated than useful for bonsai.

    I thought about using my hydrometer at one time to try to figure out an approximate concentration of nutrients similar to the EC calibration curve you mentioned. I figured I could get the specific gravity of a near 100% solution of nutrients and plain water and get an idea from there...
     
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  11. sorce

    sorce Nonsense Rascal

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    Thanks Leo!

    Now..
    When I be like...
    Eff PH!

    Everybody knows why!

    Sorce
     
  12. I have a fertilizer talk for Orchid Growers, and I did a rewrite for my local bonsai club. I'm not happy with the bonsai version yet. But some day I'll post a detailed article for the Articles and Tutorials forum - but right now I don't have time other than to offer my short little essays. Its a deep, multilayered subject. And there are many complications.

    Your water available for irrigation - if you know its chemistry, then you can choose your potting mix design to best use your water chemistry.

    Fertilizer(s) used should be based to optimize both the chemistry of your irrigation water, and the chemistry of your potting mix.

    These 3 components are closely interrelated, one affects the other. AND the whole system is affected by your climate.

    You see? a two variable system is complicated enough, but really we have 4 independent variables that interact. It will never be totally simple.

    We can control water, potting media and fertilizer choices. Environment and climate can be modified, but are much more difficult to control.
     
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  13. M. Frary

    M. Frary Bonsai Godzilla

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    Mio Michigan
    What's PH?
     
  14. sorce

    sorce Nonsense Rascal

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    Location:
    Berwyn, Il
    "PH balanced for a woman"
    Remember that commercial?

    Ehh its for women!

    Sorce
     
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  15. drew33998

    drew33998 Omono

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    But strong enough for a man
     
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  16. I know this was a response to Sorce's humor. But I am sometimes noted for not having any sense of humor. So for the less humorous in the audience

    it is written ''pH'', where the lower case ''p'' stands for ''the inverse log of the ion concentration'' the ''H'' stands for hydrogen ion. So pH is actually a measurement of hydrogen ion concentration in the water solution. Because the measurement is expressed as the inverse, the smaller the number, the more hydrogen ions in the solution, the more acidic the solution. So pH from 0.0 to 6.9 are acidic, 7.0 is neutral, 7.1 to 14 is considered caustic or basic. Lye and wet concrete paste are caustic, both have pH between 12 to 14. Vinegar is weak acid, pH around 4.0, battery acid is around pH 1.0.
     
  17. Mellow Mullet

    Mellow Mullet Masterpiece

    Yes, Leo is right on this. I work in a lab at a chemical plant. pH meters, expensive lab quality ones, are cantankerous on their best days, and a pain to calibrate. And, I have seen two meters side by side, both calibrated, give different results for the same solution (+/- .5). pH paper, like he says, is a "ball park" result, and that is using lab quality stuff. We have an effluent test for pH, it has to be 12.5 or greater before it is discharged for further treatment, it is checked with pH paper by operators before it is brought to the lab and checked with the meter. I have observed samples that had a 12 -13 pH with paper read 10 or 11 on a meter.

    I used to have a 150 gallon aquarium, and periodically I would do a half water change on it. The water out of the tap was 8.5 - 8.7 ph, I used to struggle trying to adjust it closer to 7.0, and never could maintain it, and hour or so later it would be close to 8.5 again, no matter how much phosphoric acid I added (within reason). The reason, the tap water, as most is, was buffered to help maintain a certain pH (this keeps it from eating pipes and leaching compounds from plumbing items). So, if you are using tap water to water your trees, there isn't much you can do anyway. I quit worrying about the pH in the tank, it stayed around 8.5, and the plants and fish thrived.

    As, Leo said, pH is a red herring, unless you access to a lab, the average Joe has no way to accurate way to measure it. I think soil composition (loose, well draining) and watering (maintaining proper moisture content) is way more important than how much fertilizer you use or pH.

    John
     
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