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Why can't ph buffer...
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Questions [Completed] Why can't ph buffer 7 solutions be reused

9 Posts
7 Users
Topic starter

Hi percy growers. 

It's been quite sometine since I last had any interaction with the forum. I now feel like a totally different person after sorting out my demons. And I've now started growing again. I can't remember the person that I used to be. Which is an absolute blessing. That person is gone and I'm now on the mend. 

Apologies to all that I may have upset in the past. 

I'm now in the process upon running 3 plants in coco and 4 in hempy buckets. I calibrate my ph cheapo ph pen everytime I use it. 

One thing that I can't get my head around is how I continue to waste ph buffer 7 solutions.

Its an apparent fact that you can't reuse the solution, and I can't get my head around why this is the case.

How does the pH buffer solution know that its been used to calibrate a pH pen. Why can't it be tipped back into the bottle to be use again.



ℛ𝓮𝓪𝓵 𝓷𝓲𝓬𝓮 𝓽𝓸 𝓫𝓮 𝓫𝓪𝓬𝓴 𝓹𝓸𝓼𝓽𝓲𝓷𝓰 𝓸𝓷 𝓽𝓱𝓮 𝓯𝓸𝓻𝓾𝓶 𝓪𝓰𝓪𝓲𝓷 𝓪𝓯𝓽𝓮𝓻 𝓱𝓪𝓿𝓲𝓷𝓰 𝓵𝓸𝓬𝓴𝓮𝓭 𝓶𝔂𝓼𝓮𝓵𝓯 𝓸𝓾𝓽 𝓸𝓯 𝓶𝔂 𝓪𝓬𝓬𝓸𝓾𝓷𝓽.
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7 Answers

I do mine once a month Thumbs Up  

Posted by: @thestars

Apologies to all that I may have upset in the past.

Nobody here you have upset mate, its good to have you back Smile

Posted by: @thestars

Its an apparent fact that you can't reuse the solution, and I can't get my head around why this is the case.

The pH buffer solution is set at a set pH. When you use it with a pH Pen, water or other contaminants may get into the solution. This will alter the pH and then it wont calibrate properly. Its bets to us a small amount, and throw it away. Also, it doesn't need doing every time you use it. Once a week should be plenty. 


"Keep away from people who try to belittle your ambitions. Small people always do that, but the really great make you feel that you, too, can become great.”
― Mark Twain


You dont want to mess up your ph buffer bottle by adding back used solution 👍

I never grow a plant, it grows me.

monkeydo monkeydo November 10, 2021 2:34 pm

I use an Apera ph meter and it comes with 2 calibration fluids. The instructions say to use the solution 5 times before replacing it. I wonder if you had a small test bottle that you could cap up after use. You could certainly test some used fluid against some fresh fluid to see if there’s a difference but I would definitely NOT pour used the solution back into the stock bottle. It would certainly ruin the other fluid eventually.

StarCodex StarCodex Topic starter November 10, 2021 8:57 pm

Thank you each and everyone of you for your answers. 

I was thinking. 

Can you still not even reuse the pH buffer solution even when I continue to rinse the probe in distilled water after each time I use it. 


I would reckon you can reuse it if you don't take the piss. Obviously contamination will alter the pH a bit, but not as much as the makers of the solution would have you believe.


You could if you wiped all the distilled water off but some probes have a sponge like absorber so each time you do that you will be altering the ph of the calibration solution making it a useless reference point to calibrate to.

The fact that your calibrating means you want your probe to be correct. So discard and use fresh solution each time.

It's pretty cheap and lasts long if you use a narrow vessel to do the test or calibration that way you use less solution than a wider vessel. You only need to cover a slight bit above sensor probe with liquid.

Also adding the used solution back to container will mess up the rest of the solution and keeping the small amount separate will change the properties of your small amount if solution due bigger temp fluctuations as with such low volume of liquid being stored. Plus multiple contacts with air/dust etc.

Use fresh and discard if possible, leave a bit out for a day or two it will discolour 👍

I never grow a plant, it grows me.


I buy big bottles and I pour X amount in small medication bottles. Use it 4-5 times. Stored in brown bottles in the dark. I shake the excess water off the probes thoroughly. I use 4 and 7 and the meter accepts it. If your suspicious of it just stick your probe in some good stuff and see what it reads. If your buffers read right, your right. If it's way off your meter shouldn't accept it. Imo. I use mine as much as the next guy I guess? That means 8-10+ min a day.

Good luck.


Why are you using the solution 8-10+ times a day?


I never grow a plant, it grows me.

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