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Discussion Starter · #1 ·
Ok, I just went to about 10 of my local stores, and of course, only one of them actually carries the calibration solution.

Of course, the expiration date is 03 07 . All 3 packets. Since we know it's "expired" how accurate is it going to be?
 

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Why did you buy pH calibration solution that is past the expiration date?
 

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Discussion Starter · #3 ·
Well, I thought I was pretty clear. No one in my area, which is an area that spans about 100 miles carries the product. Therefore since no one in 100 miles of where I live carries this product but one store, I have but only one choice to buy something even though it is expired. Granted it is only expired by 2 months. I've eaten twinkies older than that and they were still good.

So, for those that have dealt with calibration solutions, has anyone ever used solution that is/was expired. If you have was it still accurate?
 

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I don't understand why you didn't order pH calibration solutions from BigAlsonline, ThatFishPlace, DrsFosterSmith, etc when you found out that your's was out of date.

Who can predict the pH of the outdated solutions that you have? (Where did H+ or OH- go?)

You can always make your own calibration solutions.
 

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Why don't you calibrate with your solution and check what your meter or controller reads against your pH test kit? Chances are good you're not going to be far off. If you are doing EI, your really don't need the exact pH anyway because the kH-pH relationship is for pure water with carbonate (the fertilizer kind of ruins that) and you are going to slowly decrease you pH as low as possible anyway, regardless of what the chart tells you. Plants don't care what your meter reads. Just ask them. As long as you are close a controller can use that number as an index (a dang good one, too) to keep your CO2 relatively stable.
 

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Discussion Starter · #6 ·
I don't understand why you didn't order pH calibration solutions from BigAlsonline, ThatFishPlace, DrsFosterSmith, etc when you found out that your's was out of date.

Who can predict the pH of the outdated solutions that you have? (Where did H+ or OH- go?)

You can always make your own calibration solutions.

I know I can always order the stuff, and I have already done that. However, I needed to have it calibrated yesterday versus a week from now.
 

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Discussion Starter · #7 ·
Why don't you calibrate with your solution and check what your meter or controller reads against your pH test kit? Chances are good you're not going to be far off. If you are doing EI, your really don't need the exact pH anyway because the kH-pH relationship is for pure water with carbonate (the fertilizer kind of ruins that) and you are going to slowly decrease you pH as low as possible anyway, regardless of what the chart tells you. Plants don't care what your meter reads. Just ask them. As long as you are close a controller can use that number as an index (a dang good one, too) to keep your CO2 relatively stable.
The reason I am unable to do that, is I am slightly color blind, and it's extremely difficult for me to tell the colors in the kits. It's a good idea. I will have the wife help me do that.

Thanks for the suggestion.
 
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