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MasFina
Snow Shredder


Registered: 05/08/06
Posts: 788
Loc: Mountains
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How do you Test a PH Probe?
#5731355 - 06/09/06 04:31 PM (17 years, 8 months ago) |
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I wanna see if this thing is accurate. Is there any substance that has a consistent ph on which I could test it?
-------------------- A Good Substrate: Poo With Extras Good Liquid Culture, Step by Step Timer Modification PM me if you are interested in buying 140ml syringes. $6 each + $7 shipping
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monstermitch
Growing in Bags Doesn't Work


Registered: 02/10/06
Posts: 3,911
Loc: Arizona Bay
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Re: How do you Test a PH Probe? [Re: MasFina]
#5731376 - 06/09/06 04:43 PM (17 years, 8 months ago) |
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I test mine against strips.
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creamcorn
mad scientist


Registered: 03/13/06
Posts: 2,962
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Re: How do you Test a PH Probe? [Re: monstermitch]
#5731391 - 06/09/06 04:50 PM (17 years, 8 months ago) |
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pure distilled water should be totally neutral, 7.0
they sell calibration solutions too, usually at 4, 7 and 10, as some meters have multi-point calibration systems that require you to test it above and below neutral. calibration solutions are really inexpensive, either ordered on-line or check a pool store if you live in such a climate as where people buy swimming pools they'll have it there
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MasFina
Snow Shredder


Registered: 05/08/06
Posts: 788
Loc: Mountains
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Re: How do you Test a PH Probe? [Re: creamcorn]
#5731399 - 06/09/06 04:54 PM (17 years, 8 months ago) |
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I can't really drive anywhere right now. I was hoping to find something around the house I could use. Thanks though
-------------------- A Good Substrate: Poo With Extras Good Liquid Culture, Step by Step Timer Modification PM me if you are interested in buying 140ml syringes. $6 each + $7 shipping
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creamcorn
mad scientist


Registered: 03/13/06
Posts: 2,962
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Re: How do you Test a PH Probe? [Re: MasFina]
#5731405 - 06/09/06 04:57 PM (17 years, 8 months ago) |
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distilled water is your only bet i think as far as things around the house... other stuff will get you in the ballpark but not accurate enough to know your meter is accurate!
even cheap digi probes are pretty precise usually, but need to be calibrated to be accurate (yeah there's a difference between precise and accurate ) and usually needs to be re-calibrated each time you change batteries...
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MasFina
Snow Shredder


Registered: 05/08/06
Posts: 788
Loc: Mountains
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Re: How do you Test a PH Probe? [Re: creamcorn]
#5731434 - 06/09/06 05:09 PM (17 years, 8 months ago) |
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It prolly is accurate enough. I'm just in denial of my casings stubborn ph
-------------------- A Good Substrate: Poo With Extras Good Liquid Culture, Step by Step Timer Modification PM me if you are interested in buying 140ml syringes. $6 each + $7 shipping
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RogerRabbit
Bans for Pleasure


Registered: 03/26/03
Posts: 42,214
Loc: Seattle
Last seen: 11 months, 22 days
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Re: How do you Test a PH Probe? [Re: MasFina]
#5731479 - 06/09/06 05:36 PM (17 years, 8 months ago) |
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You can't test a soil probe type ph tester in water. For water, you want the glass bulb type, and they make special calibration solutions. For soil, Agar had a probe he trusted, but I don't know where he got it. All the soil probes I've found are extremely inaccurate with sterile or pasteurized media. I recommend squeezing a bit of water out of the compost or casing mix, then using a paper test strip. Once you figure out how much lime to use, just use that amount every time. I haven't needed to test ph in at least two years, so no need to buy an expensive tester. RR
-------------------- Download Let's Grow Mushrooms semper in excretia sumus solim profundum variat "I've never had a failed experiment. I've only discovered 10,000 methods which do not work." Thomas Edison
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MasFina
Snow Shredder


Registered: 05/08/06
Posts: 788
Loc: Mountains
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Re: How do you Test a PH Probe? [Re: RogerRabbit]
#5731532 - 06/09/06 05:50 PM (17 years, 8 months ago) |
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Well I checked mine against a wall mart test tube type with a little green pill and a color chart. It concurs with the probe. Maybe I'll get some strips too. My peat moss (Scotts)must be much more acidic than all of the brands people are using on here. I had 7 teaspoons hl to 6 cups peat with 3 cups osyter shell flour and it was 6.2ish. I just added 2 more teaspoons hl, so we'll see what it's at tommorow. It seems to take a full day for the ph to stop falling.
-------------------- A Good Substrate: Poo With Extras Good Liquid Culture, Step by Step Timer Modification PM me if you are interested in buying 140ml syringes. $6 each + $7 shipping
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monstermitch
Growing in Bags Doesn't Work


Registered: 02/10/06
Posts: 3,911
Loc: Arizona Bay
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Re: How do you Test a PH Probe? [Re: MasFina]
#5731610 - 06/09/06 06:15 PM (17 years, 8 months ago) |
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monstermitch
Growing in Bags Doesn't Work


Registered: 02/10/06
Posts: 3,911
Loc: Arizona Bay
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Re: How do you Test a PH Probe? [Re: MasFina]
#5731612 - 06/09/06 06:16 PM (17 years, 8 months ago) |
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MasFina
Snow Shredder


Registered: 05/08/06
Posts: 788
Loc: Mountains
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Re: How do you Test a PH Probe? [Re: monstermitch]
#5731670 - 06/09/06 06:38 PM (17 years, 8 months ago) |
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Jeez. Too much for me. I think I'll get strips. And once I get those I think I'll have all the supplies I'll need for a long time. I just gotta find a horse farm though...
-------------------- A Good Substrate: Poo With Extras Good Liquid Culture, Step by Step Timer Modification PM me if you are interested in buying 140ml syringes. $6 each + $7 shipping
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soma_seeker
Stranger in aStrange Land


Registered: 04/02/06
Posts: 367
Loc: Down under
Last seen: 4 months, 8 days
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Re: How do you Test a PH Probe? [Re: MasFina]
#5732816 - 06/10/06 12:29 AM (17 years, 8 months ago) |
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As a chem major i should have a better idea about this than i do but i'll have a stab at it for you. There are several items from around the house that you could use to calibrate (hey its 4:20) ur pH probe but it will depend on wether you can find out their purity (from contents on the label).
my first bet would be vinegar, which is a solution of acetic acid in water. if you can find the percentage of acetic acid written on the label then let me know and i'll try and analyse it further, if not i believe vinegar is usually 5% acetic acid, which correlates to a pH of 2.4
If the bottle is half empty or has been left open this will also effect its pH due to proton exchange with the moisture in the air.
this url also quotes a few other household items you could try but bare in mind the values are for PURE substances.
http://web.jjay.cuny.edu/~acarpi/NSC/7-ph.htm
hope i've helped, let me know how you go.
Dyl
-------------------- Taking a psychedelic is analogous to life, if you dwell on reaching the end you'll never enjoy the trip!
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MasFina
Snow Shredder


Registered: 05/08/06
Posts: 788
Loc: Mountains
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Re: How do you Test a PH Probe? [Re: soma_seeker]
#5734488 - 06/10/06 02:35 PM (17 years, 8 months ago) |
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My white distilled vinegar says "adjusted with water to 5% acidity."
I also have 100%, "natural strength" lemon juice
-------------------- A Good Substrate: Poo With Extras Good Liquid Culture, Step by Step Timer Modification PM me if you are interested in buying 140ml syringes. $6 each + $7 shipping
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soma_seeker
Stranger in aStrange Land


Registered: 04/02/06
Posts: 367
Loc: Down under
Last seen: 4 months, 8 days
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Re: How do you Test a PH Probe? [Re: MasFina]
#5737279 - 06/11/06 06:38 AM (17 years, 8 months ago) |
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Quote:
MasFina said: My white distilled vinegar says "adjusted with water to 5% acidity."
thats just a less scientific way of saying the solution is diluted with water to an acetic acid conc. of 5%, so like i mentioned it should have a pH of approx. 2.4, bearing in mind this value would tend to increase if it has been allowed to interact with the air.
-------------------- Taking a psychedelic is analogous to life, if you dwell on reaching the end you'll never enjoy the trip!
Edited by soma_seeker (09/09/06 06:53 AM)
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