Page 1 of 2 12 LastLast
Results 1 to 15 of 19

Thread: pH reference solutions

  1. #1
    Join Date
    Oct 2011
    Location
    Melbourne
    Posts
    1,907

    Default pH reference solutions

    Wondering if anyone knows where to get cheap 4pH + 7pH reference solutions? They seem to be exorbitantly over-priced on fleabay etc. unless you order in from O/S.

  2. #2
    Join Date
    Feb 2013
    Location
    NSW, Sydney
    Posts
    204

    Default

    Hey mate, did you end up getting a co2 ph controller?

    Can't help with where to get solutions...
    90x50x50 Planted with co2pro and EI Fert

  3. #3
    Join Date
    Oct 2011
    Location
    Melbourne
    Posts
    1,907

    Default

    Hi JetMan. I was never in the market for a CO2 controller.. maybe you've got me mixed up with someone else?

  4. #4

    Default

    Hey guys why not make your own buffers.
    We do it all the time especially to calibrate Digital pH Meters and pH Controllers.

    Here is the recipe sheet:
    Chemicals required:
    1) 98-99% Potassium DiHydrogen Phosphate KH2PO4 (Sigma Tech Grade 500g ~$6.00)
    Solution: 0.1M made by dissolving 13.60g and make to 1L with Distilled Water
    2) 98% Sodium Hydroxide NaOH (Bunnings, Diggers is ok ~$4.40 for 500g)
    Solution: 0.1M made by dissolving 4.00g and make to 1L with Distilled Water

    Use the stock 0.1Molar made as above to make 200ml each time with Distilled Water:

    Common pH Meter CALIBRATION BUFFER (phosphate)
    pH Range: 6.0 - 8.00
    100 ml of 0.1 M KH2PO4 PLUS mls of 0.1 M NaOH to add then make to 200ml with distilled water
    pH mls of 0.1M NaOH to be added
    6.00 11.2
    6.20 16.2
    6.40 23.2
    6.50 27.8
    6.60 32.8
    6.80 44.8
    7.00 58.2
    7.20 69.4
    7.40 78.2
    7.50 82.2
    7.60 85.6
    7.80 90.6
    8.00 93.4

    So if you want to make a calibration Buffer of pH 7.5, you put 100mls of the 0.1M KH2PO4 in a 250ml cylinder or beaker.
    Add 82.2mls of the 0.1M NaOH solution using a measuring cylinder, swirl to mix then add Distilled Water to make it all up to 200mls.
    Thats IT! you have an accurrate pH calibration buffer - it never fails especially if you make new stock solutions every year and new calibration buffer mix every 2weeks (keep 0.1M solutions sealed in the fridge [warm to ambient before using]).

    If you can't find a calibrated cylinder, beaker or flask just make the 200mls up on a digital scale with the container tared at 0g - make up to 201g with distilled water.
    David Grays Distilled Water is good and costs about $2 for 4L at most supermarkets.
    PM me if you have any probs, NB: Plastic 250ml cylinders are ~$3.50 from China or $4 from HK on eBay (just search 250ml plastic cylinder or measuring cylinder).

    CAUTION: Wear gloves, protective clothing and eye-wear when using Sodium Hydroxide 98% as it is very corrosive. Also take care with the 0.1M stock solution :-)

    - Hope all that helps.
    Last edited by GoTroppo; 14-03-15 at 04:01 PM. Reason: Added health warning at bottom - CORROSIVE

  5. #5
    Join Date
    Jun 2013
    Location
    ACT
    Posts
    13,742

    Default

    Superb information Gotroppo! thanks.

  6. #6
    Join Date
    Nov 2007
    Location
    perth
    Posts
    1,017

    Default

    Quote Originally Posted by Rebel View Post
    Superb information Gotroppo! thanks.
    Should be sticked thread!
    my 6 x 2 x 2.5

    http://www.aquariumlife.com.au/showthread.php/57768-Disco-s-new-6-x-2-x-2-5

  7. #7
    Join Date
    Jul 2006
    Location
    Brisbane
    Posts
    4,627

    Default

    That's fantastic info GT, thank you! Thread stuck
    Cheers,

    Rufus


    "I completely lost it. Well, okay, that sounded more awesome than what I really did, which was yell. And by yelling I mean sending a bunch of TEXT MESSAGES ALL IN CAPS!"

  8. #8
    Join Date
    Aug 2008
    Location
    Jandakot WA
    Posts
    361

    Default

    This topic has been explored previously: http://aquariumlife.com.au/showthrea...tion-solution.

    Unfortunately the use of home-made buffers is fraught with problems. Although these can probably be considered minor in an aquarium situation, at least two reference solutions should be used..... ideally pH 7.0 and another as close as possible to the desired measurement range. Good meters have auto calibration using either 2 or 3 reference solutions.

    Syd.
    Last edited by Graeme; 13-03-15 at 05:06 PM. Reason: added link

  9. #9

    Default

    Quote Originally Posted by sydad View Post
    This topic has been explored previously: http://aquariumlife.com.au/showthrea...tion-solution. ... Good meters have auto calibration using either 2 or 3 reference solutions.

    Syd.
    Hi Syd, I just read the old 2010 thread you linked but found it quite useless and it didn’t address the issue – COST!


    People want a cheaper than normal option for pH calibration.
    Most do not own a multipoint dual reference Lab grade pH meter and most aquariums run between pH 5.8 to pH 8.8 ... (ie close range to pH 7.0).
    A single point reference pH buffer used to calibrate a dry glass membrane electrode will be relatively accurate to 2 pH units (ie calibrated at ph 7.0 is ok for ph 5.0 to pH9.0 readings 0.1 pH units).
    Very few aquarist need high resolution 2 decimal place pH readings.
    An approximate pH with a 0.1 unit resolution is fine (ie: is my water 7.5, 7.6 or 7.7, don’t care a Rat’s whether it is 7.56 or 7.65 - 7.6 is OK).


    A pH meter with ATC (Automatic Temp Calibration) is desirable as not all aquariums are at exactly 25C that the pH calibration is designed for. (eg: My Altum tank is pH 6.2 at 29C)
    Most aquarist just use a $10-$20 electronic pH pen with dry scintered glass membrane electrode. Doing dual point calibration is simply ridiculous as the aquarium water is fairly low salt and fairly clean.
    Ag/Pt pH electrodes or KOH dual reference electrodes etc are simply overkill.
    Also, some people can’t afford the $62+GST for 20 x pH 7.0 Cole / Palmer or Merck Standard Calibration Buffer Tablets.
    I believe this thread is of more benefit as it simply supplies a relevant cheaper ongoing option with easily obtainable chemicals available in most cities/country towns.

    To be honest, everyone should go out and buy a Lab grade pH meter and get fresh pre-prepared Standard Calibration Buffers for each calibration BUT most don't give a Rats and are happy for their $10 pH pen to be calibrated at home on the cheap to 0.1 pH units and know that they are "in the ball-park" with pH.
    Last edited by GoTroppo; 14-03-15 at 04:17 PM.

  10. #10
    Join Date
    Jun 2007
    Location
    S.A.
    Posts
    2,023

    Default

    some good info here, but in my experience with the el cheepo pH pens is they are very hit an miss, you might get one that is accurate you might not.
    myself i would rather pay the extra dollars and get a 2 point calibration pen of a better more well know brand and something that is going to last, rather than just keep wasting money on cheap crap...
    ><((((>`..`..`...><((((>
    `.. , . .`.. ><((((>`..`.><((((>
    ><((((>`..`..`...><((((>
    `.. , . .`.. ><((((>`..`><((((>

  11. #11
    Join Date
    Mar 2014
    Location
    Adelaide, South Australia
    Posts
    1,084

    Default

    Quote Originally Posted by planted View Post
    some good info here, but in my experience with the el cheepo pH pens is they are very hit an miss, you might get one that is accurate you might not.
    myself i would rather pay the extra dollars and get a 2 point calibration pen of a better more well know brand and something that is going to last, rather than just keep wasting money on cheap crap...
    Couldn't agree more. And then keep it wet. Mine sits in my tank immersed constantly.
    90 litre and 300 litre journal: http://www.aquariumlife.com.au/showthread.php/57087-Ground-Zero-My-venture-into-aquascaping-begins-Now-3-tanks

  12. #12

    Default

    These buffers seem reasonably priced: $9 for 500ml

    http://www.anpros.com.au/buffer-and-...ode-solutions/

  13. #13
    Join Date
    Jun 2007
    Location
    S.A.
    Posts
    2,023

    Default

    These buffers seem reasonably priced: $9 for 500ml
    that is "very" cheap, we sell the disposable pouches of Hanna pH fluids at work which are 20ml and they are quite a bit dearer than what they are charging for a 500ml bottle of there fluids...
    ><((((>`..`..`...><((((>
    `.. , . .`.. ><((((>`..`.><((((>
    ><((((>`..`..`...><((((>
    `.. , . .`.. ><((((>`..`><((((>

  14. #14
    Join Date
    May 2015
    Location
    South Australia
    Posts
    67

    Default

    For anyone that is interested Chem-Supply have PH buffer on special in Adelaide - $6.00 + GST for 500ml, until 30nov

    https://www.chemsupply.com.au/#

  15. #15

    Default

    I wonder what their shipping costs are like... annoys me to have to create an account to find out! Any clue Jitank?

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
  •