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CO2 present in the morning

kilnakorr

Member
Joined
16 Mar 2020
Messages
208
Location
Denmark
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.
FQ5RPCZgX8y8ehyz8

after lots of shaking / blowing air into same vial.
XgfcKv7wHVXugdFW8
.

Anyone have ideas on why so much CO2 is still present, or could it be something else?
 
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.
 
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.
20200316-074609.jpg

20200316-074853.jpg


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.
 
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.
 
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.
 
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.
20200316-161048.jpg
 
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.
 
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
 
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

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