pH with Ambient co2 Readings

[jda]

I wrote down some pH values in my tank with the corresponding co2 readings in my home as I turned the AC on over the last few days.

I was hoping that others could post and we could start to understand the drop in pH as co2 goes up.

I measured with a $50 amazon co2 meter and a $20 Amazon pH pen that I just calibrated - these are not super accurate tools. Took all readings at 21:30, so near the end of my light cycle where the pH should be the most high - I did not take low readings.

421 co2, 8.41 pH
512 co2, 8.39 pH
665 co2, 8.24 pH
719 co2, 8.17 pH

Anybody else have any numbers as pH and co2 moves up or down?

 

[Randy Holmes-Farley]

I wrote down some pH values in my tank with the corresponding co2 readings in my home as I turned the AC on over the last few days.

I was hoping that others could post and we could start to understand the drop in pH as co2 goes up.

I measured with a $50 amazon co2 meter and a $20 Amazon pH pen that I just calibrated - these are not super accurate tools. Took all readings at 21:30, so near the end of my light cycle where the pH should be the most high - I did not take low readings.

421 co2, 8.41 pH
512 co2, 8.39 pH
665 co2, 8.24 pH
719 co2, 8.17 pH

Anybody else have any numbers as pH and co2 moves up or down?

Alk plays a strong role. What was your alk?

 

[jda]

6.8 when it is time to turn my CaRx up and 7.2 when it reaches the top and stabilizes after I up the bubbles and drip rate. I try and keep it around 7, but with growing things, this is nearly impossible.

 

[Dennis Cartier]

There is a python module that can calculate the relationship for you. @arking_mark

 

[arking_mark]

There is a mathematical model for pH, CO2, and alk. The Python library is called PyCO2SYS.

 

[jda]

Who do you know that can use this? ...like in the real world?

Have you all actually used this? Tried this a while back with a BS and MS in computer science and the results that I got were not what I would expect. I am sure that I got some of the parameters wrong since I spent about 10 minutes reading on the input parameters, but I would guess that there might not be 5 folks on here who even know how to install Python, let alone write something in it.

I tried 7.0 dKh at 125ppm, 1100 co2, salinity at 35 and temp at 75 ish and it gave me a pH of 6.43704277987489.

import PyCO2SYS as pyco2

args = { "par1" : 125, "par1_type" : 1, "par2" : 1100, "par2_type" : 4, "salinity" : 35, "temperature": 23.5, }

results = pyco2.sys( **args )

print( results["pH"] )

 

[KStatefan]

The highest I have seen on my CO2 is 1100 this week. It has been very hot and my daughter is home from college this week but I did not look at PH at the same time.

 

[arking_mark]

 

[jda]

Using 2520 for alk, I got:

421 co2 - 8.06 pH
719 co2 - 7.86 pH

Unless I got the params wrong again, this calculator might not be all that great for tanks inside of homes.

 

[arking_mark]

Using 2520 for alk, I got:

421 co2 - 8.06 pH
719 co2 - 7.86 pH

Unless I got the params wrong again, this calculator might not be all that great for tanks inside of homes.

pyCO2SYS is a modeling tool and not a plug and play calculator. Took me several trys to understand the model and how to configure the parameters.

 

[arking_mark]

pyCO2SYS is a modeling tool and not a plug and play calculator. Took me several trys to understand the model and how to configure the parameters.

 

[arking_mark]

Note the pH Total is not commonly used. Most people in the hobby use NBS.

 

[jda]

I am just trying to give people an idea of how much they are impacting their pH by closing up their windows for the summer or winter and having co2 accumlate. As you can tell even with this model, that it can be a huge deal.

Even with the NBS pH standard, it is low for tanks with a co2 around 425 compared to actual measurements, but it can still tell a story with how much elevated co2 in the inside air matters.

I also understand that there are other factors in a tank, like photosynthesis that this model does not appear to track... and even if it did, I have no idea how to measure this to input a number anyway.

 

[The_Paradox]

387 outdoors right now
450-500 indoors this time of year.
Alk 30 day avg is 11.93 and my pH is deadnuts stable at 8.4 during the day. Fun fact is CO2 is lowest in the cabinet.

 

[arking_mark]

I am just trying to give people an idea of how much they are impacting their pH by closing up their windows for the summer or winter and having co2 accumlate. As you can tell even with this model, that it can be a huge deal.

Even with the NBS pH standard, it is low for tanks with a co2 around 425 compared to actual measurements, but it can still tell a story with how much elevated co2 in the inside air matters.

I also understand that there are other factors in a tank, like photosynthesis that this model does not appear to track... and even if it did, I have no idea how to measure this to input a number anyway.

Aquarium pH Distilled

I just wanted to share my understanding of reef pH which is mostly based on: Low pH: Causes and Cures by Randy Holmes-Farley - Reefkeeping.com Many would agree that reef tanks can be successful with pH between 7.8 – 8.5 NBS and daily swings as great as 0.5 NBS. Natural pH levels in our ocean...

www.reef2reef.com

 

[jda]

If anybody wants to use this on their own, here is some code with a guess at the difference in the model and my tank pH, on average. Disclaimer: I have written a lot of code in my life, but never much in python... so no judgement.

import PyCO2SYS as pyco2
import sys

dkh = float(sys.argv[1])
alk = dkh * 360
co2 = sys.argv[2]

print( "dKH:", dkh, ", Alk:", alk)
print( "co2:", co2)

args = { "par1" : alk, "par1_type" : 1, "par2" : co2, "par2_type" : 4, "salinity" : 35, "temperature": 23.5, }

results = pyco2.sys( **args )

# print( "ph Tot:", results["pH"] )
print( "pH NBS:", round( results["pH_nbs"], 3)  )
print( "tank pH Est:", round( results["pH_nbs"] + .22 , 3) )

 

[arking_mark]

If anybody wants to use this on their own, here is some code with a guess at the difference in the model and my tank pH, on average. Disclaimer: I have written a lot of code in my life, but never much in python... so no judgement.

import PyCO2SYS as pyco2
import sys

dkh = int(sys.argv[1])
alk = dkh * 360
co2 = sys.argv[2]

print( "dKH:", dkh, ", Alk:", alk)
print( "co2:", co2)

args = { "par1" : alk, "par1_type" : 1, "par2" : co2, "par2_type" : 4, "salinity" : 35, "temperature": 23.5, }

results = pyco2.sys( **args )

# print( "ph Tot:", results["pH"] )
print( "pH NBS:", round( results["pH_nbs"], 3)  )
print( "tank pH Est:", round( results["pH_nbs"] + .22 , 3) )

Prettier than my code.

 

[NanJ]

The pH on our 2 year old tank (300 g) was running 7.8-7.9. We were at wits end trying to figure out how to get the pH higher - opening windows if weather permitted, researching air exchangers or installing fans to pull air out of the fish room where the sump is. We were getting a little crazy….

Our engineer son said, you need data before you can make a plan. So we got a CO2 meter. Turns out the CO2 runs 600-800 ppm even with the windows closed and HVAC on. That level didn’t seem like it should drive the pH too far down.

We got distracted from this problem with health issues and never did anything . Lo and behold, at about 3 1/2 years old the pH of the tank increased to optimal levels of 8.2-8.4 with no changes or input from us. I have heard that it takes time for a tank to mature - guess that was it?!

We keep Alkalinity about 10 and have mostly LPS corals.

 

[Toob]

The pH on our 2 year old tank (300 g) was running 7.8-7.9. We were at wits end trying to figure out how to get the pH higher - opening windows if weather permitted, researching air exchangers or installing fans to pull air out of the fish room where the sump is. We were getting a little crazy….

Our engineer son said, you need data before you can make a plan. So we got a CO2 meter. Turns out the CO2 runs 600-800 ppm even with the windows closed and HVAC on. That level didn’t seem like it should drive the pH too far down.

We got distracted from this problem with health issues and never did anything . Lo and behold, at about 3 1/2 years old the pH of the tank increased to optimal levels of 8.2-8.4 with no changes or input from us. I have heard that it takes time for a tank to mature - guess that was it?!

We keep Alkalinity about 10 and have mostly LPS corals.

Is it at that 8.2-8.4 range with the same old 600-800 CO2 levels? I'm guessing you have a lot more coral than you did 3 years ago?

 

[NanJ]

Is it at that 8.2-8.4 range with the same old 600-800 CO2 levels? I'm guessing you have a lot more coral than you did 3 years ago?

Yes, CO2 levels remain in that range year round. And, yes, we do have a lot more corals - not grown out to the point of carpeting but pretty much out of real estate for new frags to allow room to grow.