pH Testing Irregularities?

[Emily in Everett]

Puzzling over wild irregularities in results when pH testing. See photo below. I took 4 vials from the same place in the same tank. Left two vials got 3 drops from the left bottle. Right two vials got 3 drops from the right bottle. Shook both bottles first. 

My two questions:

1. What the heck is my pH??? 

• 6.0 per yellow vial? 
• 6.4 per a 7-in-1 aquarium test strip?
• 6.8 to 7.0 per the green vials?
• 7.6 per the blue vial?

2. Why so much variation??? I've completely lost faith in all these methods...

[nabokovfan87]

One of the big things I'm learning about with the liquid tests is that residuals in the vials can alter the tests. You'd want to rinse/clean them as best you can, then go ahead and before use fill/empty them with tank water to ensure that everything is reading from the tank itself and not anything remaining in the vial.

This may or may not be applicable to what you're seeing.

When you see something in the 7.0+ range I tend to use the additional PH test as well.

On 4/20/2023 at 6:21 PM, Emily in Everett said:

• 6.0 per yellow vial? 
• 6.4 per a 7-in-1 aquarium test strip?
• 6.8 to 7.0 per the green vials?
• 7.6 per the blue vial?

Along with the above, using a timer to record and read at the precise time is also important. Letting tests sit longer does alter their results.