Shop Orchid Care OrchidTalk Orchid Forum Weather Station Links Nursery

Welcome to OrchidTalk Orchid Forums


The Friendliest Orchid Community on the Internet!


  •  » Learn to Repot your Orchids
  •  » Learn Orchid Care Tips and Secrets
  •  » Find the perfect Orchid for your Growing Environment
  •  » Chat with Orchid Growing Professionals

OrchidTalk - "Bringing People Together to Grow Orchids Better!"


Let us help you grow your Orchids better; Join our community today.


YES! I want to register an account for free right now!


Register or Login now to remove this advertisement.

Page 1 of 2 12 LastLast
Results 1 to 10 of 16

pH and TDS

This is a discussion on pH and TDS within the General Orchid Culture forums, part of the Orchid Culture category; Fertilizers are a very complex subject that do require some knowledge of chemistry sorry, Diane! ...

Click here to increase the font size Click here to reduce the font size
  1. #1
    Piper's Avatar
    Piper is offline Hangs
    Join Date
    Dec 2004
    Location
    Massachusetts
    Posts
    7,068

    Default pH and TDS

    Fertilizers are a very complex subject that do require some knowledge of chemistry sorry, Diane! and are not my area of expertise, but for the hobbyist orchid grower a basic knowledge of pH and TDS applied to your growing regime can go a long way to making your plants very happy, and possibly urging those stubborn bloomers to strut their stuff.

    pH

    pH is a measure of the hydrogen ion activity in a liquid. That sounds like Greek, so let me rephrase it: pH is a measure of acidity. The scale runs from 0-14. Zero is caustically acidic, and 14 is caustically basic that is, acid vs. base. While living organisms can specialize microclimates of high acid low pH or high base high pH, they themselves typically must live in the middle of the range, where things aren't too nasty. Our stomachs are great examples. Gastric acid has a pH of 1.5-2.0 quite low on a scale of 0-14... When everything is working fine, we don't notice, but if you vomit or burb up stomach juices eww! the acid burns your esophagus, which isn't prepared for the acidity.

    Just for fun, here are some typical pH's:

    -.05 Battery acid
    2.5 Coke that's scary!
    3.5 Orange juice
    5.0 Coffee
    7.0 Pure water
    7.35-7.45 Blood
    8.0 Sea water
    9.0-10.0 Soap
    11.5 Ammonia
    12.5 Bleach
    13.5 Household lye

    Not only will an incorrect pH burn our plants if it's wildly off, more importantly different nutrients will dissolve or precipitate out at varying pH's. That's to say, if the pH is off, a nutrient may be in your fertilizer, but your plant's not getting it. I think the latter point is the more critical one for orchid growing.

    Handheld pH monitors are commonly available in the $20-30 range.

    TDS

    TDS stands for total dissolved solids in a liquid, and is measured in parts per million PPM. These 'solids' can include salts, minerals, metals, cations and anions.

    They aren't good for us, or our plants, and orchid are particularly choosy about the quality of their water. If it's good, they'll grow like crazy! The common ways of filtering or removing solids include: reverse osmosis R/O, deionization, microfiltration, distillation and carbon filtration.

    On a PPM scale, here's what TDS looks like:

    0-50 'Pure' drinking water, acheived through R/O, deionization, microfiltration or distillation

    50-160 Carbon filtration

    170 Definition of 'hard' water

    160-400 Average tap water

    500 EPA's max contamination level

    So you can see that our tap water is pretty disgusting. Handheld TDS meters will measure TDS. You'll also see electrical conductivity EC meters available. They get you to the same place. In fact, they're one and the same thing. The only real way to measure TDS is to evaporate a water sample and weigh the junk that's left. TDS meters use the electrical conductivity of a solution to work back to the total dissolved solids. Good meters are as low as $35. PM me if you'd like sources.

    Orchids care greatly about TDS. They want fertilizer, but high salt levels will burn their leaves - badly, depending on the orchid. You want your water as pure as possible, and the right balance of fertilizer for your plants. If water doesn't flush the pot regularly, or if the plant dries out too much, all those salts get concentrated in the leaves and roots and burn 'em! To alarming degrees when serious. You simply don't know what's going on in the pot, without the ability to measure it.

    When watering, or soaking a plant, stop your sink or use a bucket, so the runoff water leachate doesn't escape. Then test the TDS of the leachate. That will tell you what you're doing to your plants.

    Ok, those are the basics. I haven't gotten into ideal leachate TDS, because I haven't figured that part out yet...

    But I'll repeat a link that Steve pointed us to, because it converts fert levels in tsps/gallon into TDS:
    Fertilizer Calculator

    Happy growing!
    Julie

  2. #2
    Brutal_Dreamer's Avatar
    Brutal_Dreamer is offline Dreaming with my eyes open...
    Real Name
    Bruce Brown
    My Grow Area
    Greenhouse
    Favorite Orchid(s)
    Cattleyas & Slippers
    Join Date
    Mar 2003
    Gender
    Male
    Location
    Arkansas
    Posts
    34,003
    Member's Country Flag

    Default

    Julie, that is great information! Thanks for taking the time to put that all into a post. I changed the link at the end of the post to point to our links thread since the other link is already in the forum.

    Cheers!
    BD

  3. #3
    Diane's Avatar
    Diane is offline Can't Re-Member
    My Grow Area
    Windowsill
    Favorite Orchid(s)
    Catts and Paphs
    Join Date
    Jun 2005
    Location
    Surprise, AZ
    Posts
    6,250
    Member's Country Flag

    Default

    Hey! I 've have nothing against chemists... in fact my sister was a chemist in a past life.... They are very usefull people to have around.

  4. #4
    Piper's Avatar
    Piper is offline Hangs
    Join Date
    Dec 2004
    Location
    Massachusetts
    Posts
    7,068

    Default

    Diane! There, there! I didn't mean to upset you, and I wasn't suggesting you were disting chemists.

    I just know how much you hate having to brush up on your chemistry, trigonometry, philately and areodynamics to grow your orchids.

    Julie

  5. #5
    Diane's Avatar
    Diane is offline Can't Re-Member
    My Grow Area
    Windowsill
    Favorite Orchid(s)
    Catts and Paphs
    Join Date
    Jun 2005
    Location
    Surprise, AZ
    Posts
    6,250
    Member's Country Flag

    Default

    Quote Originally Posted by Piper
    Diane! There, there! I didn't mean to upset you, and I wasn't suggesting you were disting chemists.

    I just know how much you hate having to brush up on your chemistry, trigonometry, philately and areodynamics to grow your orchids.

    Julie
    That's why I joined the forum - so I wouldn't have to brush up. There are so many people here who are really into the details, that they provide me with the answers - - except philately, I'm not sure how postage works into this?

  6. #6
    Piper's Avatar
    Piper is offline Hangs
    Join Date
    Dec 2004
    Location
    Massachusetts
    Posts
    7,068

    Default

    How else could we exchange plants?

    Julie

  7. #7
    Diane's Avatar
    Diane is offline Can't Re-Member
    My Grow Area
    Windowsill
    Favorite Orchid(s)
    Catts and Paphs
    Join Date
    Jun 2005
    Location
    Surprise, AZ
    Posts
    6,250
    Member's Country Flag

    Default

    You mean you STILL haven't figured out how to teletransport them??? Get going, girl!!!

  8. #8
    uncasteeb's Avatar
    uncasteeb is offline Senior Member
    Join Date
    Jul 2004
    Location
    England
    Posts
    1,666

    Default

    Very useful & informative.
    1 thing worth mentioning is that the purer the water the more dramatic the PH change when adding fert to it.
    So if you use RO or rainwater then use fert specially for it .

  9. #9
    Hoa Tony Nguyen's Avatar
    Hoa Tony Nguyen is offline Senior Member
    Join Date
    Nov 2005
    Location
    Pasadena and Costa Mesa
    Posts
    2,408

    Default

    Great informative post, Julie! We all appreciate it!
    Cheers. Hoa.

  10. #10
    Gin's Avatar
    Gin
    Gin is offline Senior Member
    My Grow Area
    Greenhouse
    Favorite Orchid(s)
    All types
    Join Date
    Sep 2004
    Location
    Missouri
    Posts
    4,831
    Member's Country Flag

    Default

    Today was Fert. day I test the water before using it , had some rain water in an 18 gal. container tested the tds. it was way high before adding the Fert . approx 235 .. could not use that so tested another 18 gal. container of rain it was approx . 11 all I could figure out it was the first rain water after a dry period . It is collected from the greenhouse roof no shingle residue .
    Ph. runs 6.5 to 7.
    Awhile back I tested runoff from various mixes , bark , Spag. , Pro Mix all were diffrent , I wrote it down somewhere if I find it will post the results . gin

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
OrchidTalk --An Orchid Growers Discussion Forum brought to you by River Valley Orchidworks. A World Community where orchid beginners and experts talk about orchids and share tips on their care, cultivation, and propagation.