Help in understanding ph needed

[Chad]

I'm scratching my head trying to understand how ph works. I've attached a pic of what I'm seeing in my water testing. Number 1 is a ph test straight from my tap. It's high, looks like 8.4. My 2nd and 3rd test are from my aquarium. The high ph test seems off the charts low, while the regular ph test seems off the charts high. What does this mean exactly? I figured the tests showed that my ph in the tank is somewhere between 7.4 and 7.6. But since they're at both ends of their respective testing spectrum I'm unsure. I also tested water that's been sitting for 24 hours and got the exact same readings as #'s 2 and 3. I've tested gh (8-10 degrees) and kh (5-6 degrees) in the past and they always show hard, but not crazy hard, water. Any insights you might have are greatly appreciated. It's been like this for some time, finally got around to fully testing my AQ and sitting water at the same time.

[Biotope Biologist]

Well 7.4-7.6 pH is not a huge range.  Your municipality could be adding something to the water to keep it basic and that 7.4-7.6 is what the water actually is once that additive dissociates. 

 

The other thing is that your plants and fish respire, things decompose, which release CO2. Which is an acid, this lowers your pH. And I would imagine with your dGH and dKH the equilibrium of this reaction favors 7.5pH.

 

Also as far as those charts go, they are confusing but what it means is they ran out of room and had to add a second row for pH. You can omit the word "high range" as it's not a qualitative (quantitative?) variable.

Edited August 26, 2021 by Biotope Biologist

[Chad]

Thanks @Biotope Biologist, your insight is appreciated and helps. So to help me understand fully, the drop in ph is likely an additive weakening from the tap water? I was curious how the fish and plants affected the water but since the resting water and tank water were so closely aligned I didn't know what think.

[Biotope Biologist]

On 8/26/2021 at 8:15 AM, Chad said:

Thanks @Biotope Biologist, your insight is appreciated and helps. So to help me understand fully, the drop in ph is likely an additive weakening from the tap water? I was curious how the fish and plants affected the water but since the resting water and tank water were so closely aligned I didn't know what think.

That's my best guess. Some municipalities add a base to the water from my understanding to prevent corrosion of the pipes.

[Mmiller2001]

On 8/26/2021 at 9:10 AM, Biotope Biologist said:

Well 7.4-7.6 pH is not a huge range.  Your municipality could be adding something to the water to keep it basic and that 7.4-7.6 is what the water actually is once that additive dissociates. 

 

The other thing is that your plants and fish respire, things decompose, which release CO2. Which is an acid, this lowers your pH. And I would imagine with your dGH and dKH the equilibrium of this reaction favors 7.5pH.

 

Also as far as those charts go, they are confusing but what it means is they ran out of room and had to add a second row for pH. You can omit the word "high range" as it's not a qualitative (quantitative?) variable.

This, and I will add that these hobby level test kits can not be trusted without calibration. 

I highly recommend a decent pH pen, long term it's cheaper, and more accurate and easily calibrated.

How much do those API test kits cost over the time of having your tank/s?

This is the cheapest I would go:

https://www.amazon.com/dp/B01ENFOHN8/ref=cm_sw_r_cp_apa_glt_fabc_5473G0BJBPKGJWAFG9HT