James_in_MN
Aquarium Advice FINatic
Does anyone know the relationship between pH and GH/KH? It seems to be somewhat unpredictable how they interact. I have two scenarios in particular that make the correlation between them unclear.
Scenario 1
I was fishless cycling my 10g tank a while back. It's a planted tank with java ferns/moss and two decent sized pieces of driftwood. My tank water is typically 7.8pH, and was in the tank during the cycle. My GH was a steady 6 degrees. My KH normally is at 4 degrees, but was dropping in my tank (to a low of 2 degrees) because I wasn't doing water changes while cycling, so the tannins built up. Despite the fact that the KH was sinking like a stone, the water remained a consistent 7.8pH.
Scenario 2
I just recently started up my 2.5g nano tank with shrimp. I transferred the backup filter and some of the java moss from my 10g tank. I also did use some of my tank water from the 10g to fill the 2.5g, mostly in an attempt to capture and transfer as many RCS as possible to it. The substrate I used in the tank, in order to avoid any scratches (acrylic), is Fluval Stratum. One thing I didn't know at the time is that this substrate has the claim that it will make the water neutral to slightly acidic. In this case, the GH only dropped from 6 to 5 degrees, and the KH dropped from 4 to 2 degrees. Unfortunately, the pH crashed to neutral, nearly killing all the RCS in the tank.
Now, from the first scenario, I had thought that the KH acted like a buffer for the pH, so as long as it was still above zero, the pH would be relatively stable. That believe was quickly debunked when the pH crashed in the second scenario. Granted, there's more Stratum per capita in the 2.5g than there is driftwood in the 10g, but it still doesn't make much sense how different the end result was considering the buffers behaved about the same way.
Here's another interesting tidbit to chew on. I was acclimating an RCS I found in my 10g tank to live in the 2.5g by periodically adding water from the 2.5g to the container the shrimp was in. After it was close to a 50/50 mix I tested the pH, and found it to be at the same 7.8 that the 10g reads. It wasn't somewhere in between 7.8 and 7.0, which is what I thought might happen, so I would think that buffers (KH) had a role to play in this.
Here's some questions I'd like to throw out there for thought. Suppose you had one gallon of 7.8pH water, and one gallon of 7.0pH water.
- If you dripped the 7.0pH water into the 7.8pH water over time, what would the pH be when complete?
- If you dripped the 7.8pH water into the 7.0pH water over time, what would the pH be when complete?
- If you immediately mixed the 7.0 and 7.8 water together, what would the resulting pH be?
Scenario 1
I was fishless cycling my 10g tank a while back. It's a planted tank with java ferns/moss and two decent sized pieces of driftwood. My tank water is typically 7.8pH, and was in the tank during the cycle. My GH was a steady 6 degrees. My KH normally is at 4 degrees, but was dropping in my tank (to a low of 2 degrees) because I wasn't doing water changes while cycling, so the tannins built up. Despite the fact that the KH was sinking like a stone, the water remained a consistent 7.8pH.
Scenario 2
I just recently started up my 2.5g nano tank with shrimp. I transferred the backup filter and some of the java moss from my 10g tank. I also did use some of my tank water from the 10g to fill the 2.5g, mostly in an attempt to capture and transfer as many RCS as possible to it. The substrate I used in the tank, in order to avoid any scratches (acrylic), is Fluval Stratum. One thing I didn't know at the time is that this substrate has the claim that it will make the water neutral to slightly acidic. In this case, the GH only dropped from 6 to 5 degrees, and the KH dropped from 4 to 2 degrees. Unfortunately, the pH crashed to neutral, nearly killing all the RCS in the tank.
Now, from the first scenario, I had thought that the KH acted like a buffer for the pH, so as long as it was still above zero, the pH would be relatively stable. That believe was quickly debunked when the pH crashed in the second scenario. Granted, there's more Stratum per capita in the 2.5g than there is driftwood in the 10g, but it still doesn't make much sense how different the end result was considering the buffers behaved about the same way.
Here's another interesting tidbit to chew on. I was acclimating an RCS I found in my 10g tank to live in the 2.5g by periodically adding water from the 2.5g to the container the shrimp was in. After it was close to a 50/50 mix I tested the pH, and found it to be at the same 7.8 that the 10g reads. It wasn't somewhere in between 7.8 and 7.0, which is what I thought might happen, so I would think that buffers (KH) had a role to play in this.
Here's some questions I'd like to throw out there for thought. Suppose you had one gallon of 7.8pH water, and one gallon of 7.0pH water.
- If you dripped the 7.0pH water into the 7.8pH water over time, what would the pH be when complete?
- If you dripped the 7.8pH water into the 7.0pH water over time, what would the pH be when complete?
- If you immediately mixed the 7.0 and 7.8 water together, what would the resulting pH be?
