Interesting pH observation.

psalm18.2

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After running pressurized CO2 for a few hours, I tested pH.
Normal pH runs at 7.6 in my tank. After several hours of CO2, pH dropped to 6.00. All normal w/ CO2.
I set the tube aside and forgot about. After several days, I look over and see the tube still full. Now the pH reads 6.8. This is the same water, not new water, in the tube.
Interesting.
 

pirahnah3

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CO2 does change the pH of the tank and will fluctuate as things stabilize from the addition. I know Dena has alot of experiance with it and im sure she will pop in here and explain it in my better terms.
 

catsma_97504

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Our tank chemistry changes by the minute in a planted tank!!

CO2 lowers pH, which is why it is critical to know your KH and GH. These 3 balance each other.

As plants become stronger and grow quicker they consume CO2 and pH rises.

One thing to note...pH changes caused by CO2 injection is not exactly a good representation of pH fluctuation. We have some chemists who could explain better, but our liquid pH testers pick up the CO2 which can make it appear your pH is crashing, but the fish are unaffected. This is because the actual pH hasn't changed all that much.

Sent from my Motorola Electrify using Tapatalk
 

bass master

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psalm18.2 said:
So as the gas fades out of the test tube, it changes pH color.
Pretty much, when CO2 dissolves into water, it forms carbonic acid, lowering your pH. The pH does in fact swing although it does not affect fish as severely as other pH swings because most other water parameters are entirely unchanged. Other means of altering pH affect many more factors which can wreck a fish's osmoregulation. When the excess CO2 gasses off, pH returns to normal as the acid disappears into the atmosphere.

I can't say I'm entirely sure what caused the pH test to rise to 6.8 rather than all the way up to 7.6 but I would guess it could be due to the pH testing reagent decomposing or reacting in some way over time giving you completely wild results. It could be partially due to the biological processes of bacteria within the vial as well.

-Bass master
 

whtmex

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If the tube was capped, it could have been the same concept as a can of soda. Only a limited amount of the CO2 would have been allowed to escape the water until the pressure balanced and trapped the rest of the CO2 in the water. Thats why soda doesn't fizz until you open it.

Soda is at a much higher level of carbonation, but same concept.
 
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psalm18.2

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CO2 lowers pH. My tank's pH sits at 7.6. Last night when I accidently gassed my fish, the pH dropped to the lowest range on test.
 
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