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1 PH drop and 20 ppm CO2

Hufsa

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22 Aug 2019
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Location
Norway
I performed a PH profile but I cant quite get the numbers to make sense to me.

I use JBL's "updated" drop checker solution which turns green at 20 ppm. I tuned injection to this ~20ppm target, possibly a hair over to a slightly yellower hue of green.
I measured the PH using a two point freshly calibrated Hanna PH checker (accuracy of ±0.2 pH and resolution of 0.1 pH).
Both my tank water and tap water has a KH of 3. The waterworks add NaOH to raise the PH of the tapwater.
My degassed tank water had a PH 7.2. The total drop was 1 to 1.1 degrees pH.

I thought that I would see less than a 1 point drop of PH seeing as I am not targeting 30 ppm.

Could someone explain to me how this works where 20ppm = 1 PH drop?
Could it have anything to do with NaOH from the water supply or high atmospheric room CO2 where the degassed sample was?
Very grateful if someone could lay it out for me :geek:

07:00 - CO2 on
07:20 - 6.7, first reading got a bit delayed
07:30 - 6.6
08:00 - 6.4
08:30 - 6.3
09:00 - 6.2
09:30 - 6.2 - Light ramp up
10:00 - 6.2 - Light full
10:30 - 6.2
11:00 - 6.2
11:30 - 6.2
12:00 - 6.2
12:30 - 6.2
13:00 - 6.1 *
13:30 - 6.2 *
14:00 - 6.1 *
14:30 - 6.1 *
15:00 - 6.1 *
15:30 - 6.2 *
16:00 - 6.1
16:30 - 6.1
17:00 - 6.1 - CO2 off
17:30 - 6.2
18:00 - 6.3 - Light ramp down
18:30 - 6.4 - Light off
19:00 - 6.5

22:30 - 6.9

*Meter was flickering a fair bit between 6.1 and 6.2 on the values marked, I think the value was very close between them.
 
Probably come from the accuracy of the ph pen. Since its +- 0.2, starting point could be in reality between 6.8 to 7.4 and this realte to the end point as well
 
Probably come from the accuracy of the ph pen. Since its +- 0.2, starting point could be in reality between 6.8 to 7.4 and this realte to the end point as well
If we assume it is not because of the ph pen, is there any other factor that can explain this?
Im just looking to understand more about the relationship around the ph drop and CO2, and I dont know if im convinced its the pen.
 
I use JBL's "updated" drop checker solution which turns green at 20 ppm. I tuned injection to this ~20ppm target, possibly a hair over to a slightly yellower hue of green.
maybe its that, since you push it higher than the 20 ppm color reference ? So with this yellower color could mean 30 ppm.

IMO its really hard to asses color correctly since it depends of the light's hue you are looking it with. If your light is warmer it gonna probably be more towards the lime while looking with a colder hue it will be towards the blue.
 
You could also add to the above…what green is the right green?

I changed my drop checker solution not so long ago to a different brand. The ‘old’ brand gave me what I would think of as a ‘good’ green, similar to the colour you are showing on yours. My newer solution gives me a noticeably darker green and has done so, literally from the day I swapped. In fact, I initially only re-filled one of the two drop checkers I use, so had different greens in the tank at the same time.

The PH value from pen testing, however, was consistent. I have therefore adjusted my perception of the shade of green I should have (at 1ph drop) to what I now get from the new solution.

My understanding is that the Co2/ph relationship is fixed. ie a 1ph drop will give you 28ppm of Co2. (I believe there may be exceptions if you are messing with your water parameters, changing Ph through addition of acids etc, but as a rule, it’s a constant) I’m happy to be corrected by smarter sciency folks mind you!
 
If someone clever knows what the ph drop should be to achieve 20ppm (I just had a quick scan online, can’t find it) you could try adjusting your Co2 to that target drop via tweaking and ph profiling and see what green you get. If you get green, albeit a bit darker, then you could tick that off as ok and you have ur new reference point. 👍 If, at that ph drop, you’re getting super dark green or heading into blue, it would maybe indicate something else is off somewhere. 🤔

All depends on how much the accurate 20ppm target matters to you…..and how much it is just bugging you I guess. 😂
 
maybe its that, since you push it higher than the 20 ppm color reference ? So with this yellower color could mean 30 ppm.
Possible, it really has been just a tiny bit of a yellower hue, and not the actual lime green that most high tech tanks run though.

You could also add to the above…what green is the right green?
A really good question. In this particular instance (with the JBL 20ppm drop checker liquid) I would say the green below is the "right green":
jbl 20ppm.jpg
If I had to describe the 20ppm JBL green it would be grass green with a yellow undertone as opposed to a cooler blue undertone.

I changed my drop checker solution not so long ago to a different brand. The ‘old’ brand gave me what I would think of as a ‘good’ green
My newer solution gives me a noticeably darker green and has done so, literally from the day I swapped. In fact, I initially only re-filled one of the two drop checkers I use, so had different greens in the tank at the same time.

The PH value from pen testing, however, was consistent. I have therefore adjusted my perception of the shade of green I should have (at 1ph drop) to what I now get from the new solution.
Interesting, this makes it even more complicated since not everyone uses the same liquid. Green is not just green and drop checker liquid isnt even just drop checker liquid apparently :oops:

similar to the colour you are showing on yours.
Not sure which photo you are referring to here, if it is the color in this post, then that is more yellow than I usually run it, and I adjusted the injection rate after taking that photo.

My understanding is that the Co2/ph relationship is fixed. ie a 1ph drop will give you 28ppm of Co2. (I believe there may be exceptions if you are messing with your water parameters, changing Ph through addition of acids etc, but as a rule, it’s a constant) I’m happy to be corrected by smarter sciency folks mind you!
I wonder if the waterworks messing with my ph counts 🤔 Its also entirely possible this is a red herring and I need to update my respect for the color green and its many variants.

If someone clever knows what the ph drop should be to achieve 20ppm (I just had a quick scan online, can’t find it) you could try adjusting your Co2 to that target drop via tweaking and ph profiling and see what green you get. If you get green, albeit a bit darker, then you could tick that off as ok and you have ur new reference point. 👍 If, at that ph drop, you’re getting super dark green or heading into blue, it would maybe indicate something else is off somewhere. 🤔

All depends on how much the accurate 20ppm target matters to you…..and how much it is just bugging you I guess. 😂
More good points, thank you 😃 The exact target doesnt really matter that much, other than that I like to understand how things work and I couldnt get these bits to fit right together 😁
I would prefer to stay in the ~20ppm area for fish safety reasons. I like to have a bit of leeway when it comes to CO2 injection, and 20 ppm allows for more of this than 30 ppm.

From the feedback I have gotten so far it seems I will need to retest a few things. Two drop checkers would be ideal, but if I suspect I am actually running more than 20ppm CO2 on my tank then switching to a 30ppm "standard" drop checker liquid would make sense, and repeating the PH profile. I have CO2Art 30ppm liquid at hand so that wont be a problem.
20ppm liquid doesnt seem to be suitable for any sort of "accuracy" (I use the term very lightly) beyond 20ppm, as you can see from their image the next step up is a greenish yellow for 50! ppm.
I assume it jumps from 20 to 50 ppm because PH is logarithmic? Basically there is no way for me to guess what my injection level is when its "slightly yellower than green" because the range shoots up so quickly. If it turns out that particular green is 30 ppm then this thread has been sort of moot. Hopefully it may still be of use to some down the road.

I will return with an update once I do another profile with 30ppm liquid :thumbup:
 
Possible, it really has been just a tiny bit of a yellower hue, and not the actual lime green that most high tech tanks run though.


A really good question. In this particular instance (with the JBL 20ppm drop checker liquid) I would say the green below is the "right green":
View attachment 187193
If I had to describe the 20ppm JBL green it would be grass green with a yellow undertone as opposed to a cooler blue undertone.



Interesting, this makes it even more complicated since not everyone uses the same liquid. Green is not just green and drop checker liquid isnt even just drop checker liquid apparently :oops:


Not sure which photo you are referring to here, if it is the color in this post, then that is more yellow than I usually run it, and I adjusted the injection rate after taking that photo.


I wonder if the waterworks messing with my ph counts 🤔 Its also entirely possible this is a red herring and I need to update my respect for the color green and its many variants.


More good points, thank you 😃 The exact target doesnt really matter that much, other than that I like to understand how things work and I couldnt get these bits to fit right together 😁
I would prefer to stay in the ~20ppm area for fish safety reasons. I like to have a bit of leeway when it comes to CO2 injection, and 20 ppm allows for more of this than 30 ppm.

From the feedback I have gotten so far it seems I will need to retest a few things. Two drop checkers would be ideal, but if I suspect I am actually running more than 20ppm CO2 on my tank then switching to a 30ppm "standard" drop checker liquid would make sense, and repeating the PH profile. I have CO2Art 30ppm liquid at hand so that wont be a problem.
20ppm liquid doesnt seem to be suitable for any sort of "accuracy" (I use the term very lightly) beyond 20ppm, as you can see from their image the next step up is a greenish yellow for 50! ppm.
I assume it jumps from 20 to 50 ppm because PH is logarithmic? Basically there is no way for me to guess what my injection level is when its "slightly yellower than green" because the range shoots up so quickly. If it turns out that particular green is 30 ppm then this thread has been sort of moot. Hopefully it may still be of use to some down the road.

I will return with an update once I do another profile with 30ppm liquid :thumbup:

I was indeed referring to that photo and my previous checker fluid gave me a colour, maybe not quite so ‘acid’ but certainly leaning that way, and my current is definitely darker than the JBL ‘correct’ green in your image. (I’m at 0.9 drop so darker rather than lighter would be expected)

Ur right, there is definitely not such a massive difference in hue on that chart, between the 20 and the 50, considering the difference in Co2 value. 😳

And I totally get you as regards ‘just wanting to understand why’. I do this lots and the rabbit holes are always fun to explore! 😂

Trying out with the 30ppm fluid seems like a good plan. Will be interesting to see if that ‘matches’ to the Co2 level you appear to have based on your profile.

We await the next instalment. 😂
 
I assume it jumps from 20 to 50 ppm because PH is logarithmic?
It's not the PH that is logaritmic but the concentration of co2

Here's an exemple explained by Tom Barr
 
degassed water is assumed to contain 2-3ppm of CO2 and there is some research paper/article that many aquascapers quote for that figure....

2ppm of CO2 in degassed water. 1 ph drop =20ppm
3ppm of CO2 in degassed water. 1ph drop =30ppm

I am currently dropping pH by 1.3 and drop checker is not yellow. My assumption is therefore that my degassed water (left outdoors its 30degreesC) has about 2ppm CO2 and therefore, 1.3pH drop is about 39ppm (drop checker turns yellow >40ppm?)
 
Maybe i miss understand what he was asking, He was asking if the CO2 concentration is higher when the PH drop or his drop checker's color changes that says 20ppm to 50pmm because the PH is logarithmic. Which i think is not correct or it would mean CO2 would be higher no matter what cause the ph drop.
 
maybe its that, since you push it higher than the 20 ppm color reference ? So with this yellower color could mean 30 ppm.

IMO its really hard to asses color correctly since it depends of the light's hue you are looking it with. If your light is warmer it gonna probably be more towards the lime while looking with a colder hue it will be towards the blue.
My two P on this one is I noticed this exact phenomenon with my new rbg light. I could get the DC to read as either yellow or nearly blue just by changing between settings on the lamp.

I have somewhere some dc that I painted the back of them white to help make reading them easier.

I’d also add that if you’re a co2 mister you often get false readings because the mist of pure co2 goes straight into the dc and you think “lovely lots if delicious co2” but you actually have more like 20ppm.

Not really relevant points. Just thinking out loud really.
 
@Hufsa - interesting - when did JBL move to a 20ppm target solution? Is it actually in lower dKH water then rather than the standard 4dKH?

EDIT: Actually, looking on the JBL website, I suspect it is their labelling of the colour chart is misleading (if not completely inaccurate):

1650619593444.png


This image suggests that is it is actually 4dKH solution, in which case the colour you describe . . .
possibly a hair over to a slightly yellower hue of green.
. . . is likely 30ppm anyway. If their image above shows the drop checker at 20ppm (probably likely) it doesn't match the colour chart anyway to my eyes.
 
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I had assumed that the ‘20ppm target solution’ would in fact have an adjusted KH in order for the drop checker to go ‘green’ at 20ppm rather than 30ppm.

Looking at the info from @Wookii above, it would seem that JBL are showing a KH4 solution going ‘green’ at PH of 6.8 when I could have sworn that the standard was that a KH4 solution will go ‘green’ at a PH of 6.6 and that this indicates 30ppm of Co2.

Article from Co2 art below:


So…..clear as mud then!! 😂
 
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