# CO2 present in the morning



## kilnakorr (16 Mar 2020)

Hi

I was just wondering why CO2 could be present in my tank in tank after many hours with no injection.
CO2 was shut off at 21.00(9.pm) and now at 8.00(8.am) there is still a decent amount present.

I have a powerhead creating good surface movement and a surface skimmer running 24/7.

I'm currently been measuring ph at intervals using drop tests (find out my ph probe was faulty), and ph drops very slowly over night.

This is ph test this morning.





after lots of shaking / blowing air into same vial.





 .

Anyone have ideas on why so much CO2 is still present, or could it be something else?


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## jaypeecee (16 Mar 2020)

Hi @kilnakorr 

Good morning!

When I click on your image links, nothing happens.

JPC


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## jaypeecee (16 Mar 2020)

Hi @kilnakorr 

If I click on your links and check the image properties, then the images appear in Google Photos > Casper Christensen.

JPC


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## Dr Mike Oxgreen (16 Mar 2020)

kilnakorr said:


> I was just wondering why CO2 could be present in my tank in tank after many hours with no injection.
> CO2 was shut off at 21.00(9.pm) and now at 8.00(8.am) there is still a decent amount present.


It’s perfectly normal. Unless you have very vigorous surface agitation, there will still be some CO₂ left over from the previous day’s injection. This is a good thing, because it means you don’t have to start injecting CO₂ quite as early before the next lighting period.  Your fish won’t care, provided the CO₂ level is reasonable and there is a good oxygen level. My drop checker doesn’t show pure blue in the morning; it’s usually a dark bluish-green.


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## jaypeecee (16 Mar 2020)

Well, that's strange. Obviously, @Dr Mike Oxgreen is not having a problem viewing your attachments! I have disabled all blockers and the links still don't work properly.

JPC


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## kilnakorr (16 Mar 2020)

jaypeecee said:


> Well, that's strange. Obviously, @Dr Mike Oxgreen is not having a problem viewing your attachments! I have disabled all blockers and the links still don't work properly.
> 
> JPC



trying something else. I hope you can view them now.


 


 

as far as I can tell (with guestimating drop test color) the ph only dropped  0.3 in 12 hrs. with no CO2 injection.
I'll keep checking the values today and update later.


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## rebel (16 Mar 2020)

kilnakorr said:


> as far as I can tell (with guestimating drop test color)


best not to guess with this. Just check the pH with a accurate meter and correlate using your kH etc.


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## kilnakorr (16 Mar 2020)

rebel said:


> best not to guess with this. Just check the pH with a accurate meter and correlate using your kH etc.


awaiting my new ph-probe. Having new soil in tank so kh/ph is not an option as this would read 200-300ppm co2.


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## Dr Mike Oxgreen (16 Mar 2020)

jaypeecee said:


> Well, that's strange. Obviously, @Dr Mike Oxgreen is not having a problem viewing your attachments! I have disabled all blockers and the links still don't work properly.


I didn’t look at the attachments. I was just commenting on the fact that the drop checker still being green in the morning isn’t unusual - at least not in my experience. And now that I can see the pictures, the morning green is a fairly dark green with a hint of blue, so it doesn’t seem abnormal to me.


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## kilnakorr (16 Mar 2020)

Dr Mike Oxgreen said:


> I didn’t look at the attachments. I was just commenting on the fact that the drop checker still being green in the morning isn’t unusual - at least not in my experience. And now that I can see the pictures, the morning green is a fairly dark green with a hint of blue, so it doesn’t seem abnormal to me.


You might be right. It's a ph 6.0 - 7.6 test so yellow to blue is 1.6 ph.


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## kilnakorr (17 Mar 2020)

just to add for others having same 'issue'. Some interesting reading about soil (especially new soil / setup): .._the released hydrogen ions react with hydrogen carbonate ions to form carbonic acid and, depending on the pH value, carbon dioxide (CO2) and water. As a result, the carbonate hardness (KH) of the aquarium water also drops because it corresponds to the bicarbonate content._

My KH has dropped quite a bit, which means CO2 is released- hence the never blue drop checker.


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## JoshP12 (18 Mar 2020)

kilnakorr said:


> just to add for others having same 'issue'. Some interesting reading about soil (especially new soil / setup): .._the released hydrogen ions react with hydrogen carbonate ions to form carbonic acid and, depending on the pH value, carbon dioxide (CO2) and water. As a result, the carbonate hardness (KH) of the aquarium water also drops because it corresponds to the bicarbonate content._
> 
> My KH has dropped quite a bit, which means CO2 is released- hence the never blue drop checker.



Aside from your substrate and nitrification, has anything else caused it drop (a mini cycle or something?)? 

If not, I’d be interested in if your tinge of green in the morning progressively changes. 

Even after a water change. 

Josh


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## kilnakorr (18 Mar 2020)

Plants234 said:


> Aside from your substrate and nitrification, has anything else caused it drop (a mini cycle or something?)?
> 
> If not, I’d be interested in if your tinge of green in the morning progressively changes.
> 
> ...



The setup is new, but filter is 'old'. No mini cycle or NH3/NH4 present.
I did a waterchange earlier today and added another drop checker in opposite side of tank. Drop checker fluid replaced, just in case.


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## kilnakorr (19 Mar 2020)

Seems the CO2 release from soil is legit. After a large waterchange yesterday, my drop checkers are blue this morning(not dark blue, but more blue than green).
Guess it will require a lot of KH testing when I get my ph probe, to tune in the CO2 injection.


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## jaypeecee (19 Mar 2020)

Hi @kilnakorr 

Excellent! Attached images are now visible.

JPC


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## kilnakorr (19 Mar 2020)

jaypeecee said:


> Hi @kilnakorr
> 
> Excellent! Attached images are now visible.
> 
> JPC


Yup. seems I used a non-valid link at first, so found an alternative
Man, I wish that ph probe would get here soon, to do some proper measuring!


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## jaypeecee (19 Mar 2020)

kilnakorr said:


> awaiting my new ph-probe.



Hi @kilnakorr 

May I ask - which pH probe did you choose?

JPC


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## kilnakorr (19 Mar 2020)

I chose some random not to expensive one. Probably some chinese thingy. Just needed one asap 
I'll probably get a new / better one once the stores and world opens up again.


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## jaypeecee (20 Mar 2020)

kilnakorr said:


> I chose some random not to expensive one. Probably some chinese thingy. Just needed one asap
> I'll probably get a new / better one once the stores and world opens up again.



Hi @kilnakorr

You are obviously aware that using a cheap (say, less than £20) pH meter may result in incorrect readings. For that reason, it is wiser to stay with recognized manufacturers such as Hanna and Extech. There are plenty of online stores -  including Amazon - from which you can get good pH meters. You may want to check your pH meter with one of the liquids listed here:

https://www.engineeringtoolbox.com/food-ph-d_403.html

JPC


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## kilnakorr (21 Mar 2020)

jaypeecee said:


> Hi @kilnakorr
> 
> You are obviously aware that using a cheap (say, less than £20) pH meter may result in incorrect readings. For that reason, it is wiser to stay with recognized manufacturers such as Hanna and Extech. There are plenty of online stores -  including Amazon - from which you can get good pH meters. You may want to check your pH meter with one of the liquids listed here:
> 
> ...


Thanks for the link. I'm not sure I'll ever find one that costs less than £20 
It seems my package is not moving at all, I decided to buy a new digital ph device to get some measurements. Calibrated it and started testing a few hours ago:
Before CO2 = 7.22 Ph
1 hr = 6.77 
2 hr = 6.58 (lights on).

With a KH of 4 this puts me at 31 ppm CO2 after 2 hours (and 7 ppm to start with). Since my KH is dropping fast in the new setup, I need further testing / tweaking CO2 the next couple of weeks / months.
Will keep testing the rest of the day, and crank it up a bit tomorrow


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## jaypeecee (21 Mar 2020)

kilnakorr said:


> Thanks for the link. I'm not sure I'll ever find one that costs less than £20
> It seems my package is not moving at all, I decided to buy a new digital ph device to get some measurements. Calibrated it and started testing a few hours ago:
> Before CO2 = 7.22 Ph
> 1 hr = 6.77
> ...



Hi @kilnakorr 

Thanks for the update.

Some people have paid less than £20 from eBay. But then run into inaccuracies, etc. I'd be interested in knowing which manufacturer and model number you chose. But, obviously, if you'd rather not say, then no problem.

So, you now have some measurements. I would suggest that 31 ppm CO2 after 2 hours is pretty good. You'll no doubt be aware that the well-known KH/pH/CO2 table is not 100% accurate. That's because other ions and compounds affect the water chemistry. I'll be interested to know at what level the CO2 stabilized with lights on.



kilnakorr said:


> Having new soil in tank so kh/ph is not an option as this would read 200-300ppm co2.



What happened about the CO2 from the soil substrate? How did you derive the figure of 200-300ppm CO2?

Is your water KH reasonably stable now and what figure(s) are you seeing?

JPC


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## kilnakorr (21 Mar 2020)

Hey @jaypeecee

It's not that I won't tell you the brand of ph-probe. It's just not posdible as it's not mentioned or visible anywhere which is why I mentioned it being some cheap chinese thing -£28.

The 200-300 ppm CO2 would be from the KH/PH/CO2 relation chart.

I do however think the green dropchecker in the morning was due to more trapped gasses in the soil from the first water added to the tank. As my KH is still dropping the CO2 from that reaction has no problem leaving the tank at same rate.

The rest of the measurements today:

3 hr = 6.58
4 hr = 6.50
6 hr = 6.50
8 hr = 6.51 (lights off).

seems 6.5 is where the curve flatlines at my current injection rate. This should mean a concentration of 40 ppm CO2. However, my start would also be 7.xx ppm CO2, which I believe is false. At this point, the new soil is having to much an impact of PH and KH to be useful in estimating CO2 concentration.

KH are not stable. Tap water KH is 12, and tank is 4, so quite a drop in a few days.

Will do a 50% waterchange tomorrow and check PH/KH after being mixed for a while. Then a new day of testing PH


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## jaypeecee (22 Mar 2020)

kilnakorr said:


> At this point, the new soil is having to much an impact of PH and KH to be useful in estimating CO2 concentration.
> 
> KH are not stable. Tap water KH is 12, and tank is 4, so quite a drop in a few days.



Hi @kilnakorr 

Which soil are you using? Do the instructions advise that this soil may have an impact on pH and KH?

JPC


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## kilnakorr (22 Mar 2020)

jaypeecee said:


> Hi @kilnakorr
> 
> Which soil are you using? Do the instructions advise that this soil may have an impact on pH and KH?
> 
> JPC


I use Tropica Soil. Yes, does say it lowers PH and to do frequent water changes the first weeks.
Been using this stuff for years, just couldn't remember it lowering KH also.

Let's say this problem is solved. Next problem is getting my reactor setup to work properly, without the need for a larger canister filter


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## Wookii (22 Mar 2020)

Just to give you another data point, it takes my tank around 12 hours for CO2 to dissipate and the Ph to return to non-CO2 levels. I run a skimmer 24/7 also.


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## kilnakorr (22 Mar 2020)

Wookii said:


> Just to give you another data point, it takes my tank around 12 hours for CO2 to dissipate and the Ph to return to non-CO2 levels. I run a skimmer 24/7 also.



Thanks for the input. This has been resolved


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## nigel bentley (14 May 2020)

Dr Mike Oxgreen said:


> It’s perfectly normal. Unless you have very vigorous surface agitation, there will still be some CO₂ left over from the previous day’s injection. This is a good thing, because it means you don’t have to start injecting CO₂ quite as early before the next lighting period.  Your fish won’t care, provided the CO₂ level is reasonable and there is a good oxygen level. My drop checker doesn’t show pure blue in the morning; it’s usually a dark bluish-green.


Hi Mike, Reference the surface agitation, I have an Eheim air pump running from lights off, until 7.30 am. This around 10 hours of the air pump running. Is it possible, I'm having too much agitation during the night as Dc is dark blue in the morning? 
Thanks Nigel


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## Dr Mike Oxgreen (15 May 2020)

nigel bentley said:


> Hi Mike, Reference the surface agitation, I have an Eheim air pump running from lights off, until 7.30 am. This around 10 hours of the air pump running. Is it possible, I'm having too much agitation during the night as Dc is dark blue in the morning?
> Thanks Nigel


Since I posted above, I have actually discovered that having overnight aeration makes my ember tetras much more active and confident during the daytime photoperiod (when the air pump is off). Have a look at the “Why are my ember tetras so shy” thread. I’ve learnt that a heavily planted tank can get low on oxygen overnight because the plants are oxygen consumers when they’re not photosynthesising, and this effect is far greater than I realised.

So my aeration comes on a few hours after lights off, and runs until the CO₂ comes on the next day. Obviously you don’t want aeration at the same time as CO₂ because you’ll just be out-gassing the CO₂ that you’re adding.

And of course, now that I’m using overnight aeration, my CO₂ drop checker is much bluer in the morning - as you’d expect. But it just about reaches a medium green by the time the lights come on, and is light green within an hour or so after.

So I now think that overnight aeration is a good idea.


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## nigel bentley (15 May 2020)

Dr Mike Oxgreen said:


> Since I posted above, I have actually discovered that having overnight aeration makes my ember tetras much more active and confident during the daytime photoperiod (when the air pump is off). Have a look at the “Why are my ember tetras so shy” thread. I’ve learnt that a heavily planted tank can get low on oxygen overnight because the plants are oxygen consumers when they’re not photosynthesising, and this effect is far greater than I realised.
> 
> So my aeration comes on a few hours after lights off, and runs until the CO₂ comes on the next day. Obviously you don’t want aeration at the same time as CO₂ because you’ll just be out-gassing the CO₂ that you’re adding.
> 
> ...


Hi Mike, Thanks for your thoughts, I think I will stick with aeration time as I also have tetras. I just wanted to make sure I wasn't overdoing it. Thanks Nigel


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