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Aeration and Oxygenation with co2

Furgan

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Aeration and Oxygenation when using co2 in our aquariums.​

I have ordered 30 Neon Green ‘Rasbora’ Microdevario kubotai. On doing my research it says they like high oxygenated water.

Running a oase biomaster thermo 600 on a 170 litre aquarium with inline co2 diffuser. Planted with mostly Java trident and dwarf sag’ along salvinia. The outflow is contested to a spray bar pointing 50 degrees so the flow bounces off the opposite front glass then circulates along the substrate and then back up the tank give a distribution of co2.

From my understanding co2 reduces oxygen in the fish tank and then the plants exhale the oxygen at night! Adding oxygen via a bubbler when running co2 reduces the co2 performance- again please correct if I am wrong.

I have a good amount of surface movement - but not a massive amount as 1) I have floating plants and don’t want these blowing all around in the tank,
2) have the spray bar positioned under the water line - to reduce noise level!

With this in mind would I have enough oxygen available within the tank? Or would I be better changing or adding something. I do have a option of adding a oxygen diffuser (basically a mini bubbler that looks like a co2 diffuser- purchased from aquarium gardens) - powered with a air pump which could go on a timer or be used 24hr!

The temperature is at 23-24 so not a high temp - I understand the higher the temp the harder it is for water to maintain oxygen in the tank.

Other than the new additions, I already have 7 corydoras and 6 Otocinclus.

Any advise is appreciated - please correct me if I am wrong on any points!
Cheers
 

Wookii

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I have ordered 30 Neon Green ‘Rasbora’ Microdevario kubotai. On doing my research it says they like high oxygenated water.

Nice choice - they are beautiful little fish. I have 10 in my tank.

I think when keeping fish we have to work on the basis that all fish like well oxygenated water.

From my understanding co2 reduces oxygen in the fish tank and then the plants exhale the oxygen at night!

No, the levels of CO2 in the water column have no bearing on the levels of dissolved oxygen (DO) in the water column.

The addition of CO2 in a well/heavily planted tank can actually increase the levels of DO as the plants photosynthesise, providing all the required nutrients are available to allow them to do so.

In a newly established tank, where the plant mass is low, it can be useful to adjust the filter outlet to create more surface agitation, or add an air stone, after lights out, to help off gas the CO2 and maintain higher DO.

However when the tank is established, and the plant mass is high, this can be counter productive as the DO will often remain above atmospheric equilibrium, well after lights out, and off gassing the CO2 wil also off gas the extra O2.

On a mature planted tank, having a fair amount of surface movement is always beneficial, even though it will off gas some CO2, as it seems to help keep the CO2 levels more stable over the entire photoperiod, rather than a continuous increase from lights on, but again less surface agitation is generally required compared to a newly set up tank which generally benefits from more.

Just be careful when you get the Kubotai, and try and add them at lights out. Consider having the CO2 off for a day to allow them to acclimatise to the tank water, and reduce their stress, then add the CO2 back slowly over a couple of days to allow them to get used to it, watching out for any surface gasping.

Also be warned that Kubotai do jump - I lost a few to start with from jumping, but your surface plants will certainly help with that.

EDIT: If you add some images of your tank showing a full tank shot, and also showing the level of surface movement, it may help with specific advice.
 
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Furgan

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Nice choice - they are beautiful little fish. I have 10 in my tank.

I think when keeping fish we have to work on the basis that all fish like well oxygenated water.



No, the levels of CO2 in the water column have no bearing on the levels of dissolved oxygen (DO) in the water column.

The addition of CO2 in a well/heavily planted tank can actually increase the levels of DO as the plants photosynthesise, providing all the required nutrients are available to allow them to do so.

In a newly established tank, where the plant mass is low, it can be useful to adjust the filter outlet to create more surface agitation, or add an air stone, after lights out, to help off gas the CO2 and maintain higher DO.

However when the tank is established, and the plant mass is high, this can be counter productive as the DO will often remain above atmospheric equilibrium, well after lights out, and off gassing the CO2 wil also off gas the extra O2.

On a mature planted tank, having a fair amount of surface movement is always beneficial, even though it will off gas some CO2, as it seems to help keep the CO2 levels more stable over the entire photoperiod, rather than a continuous increase from lights on, but again less surface agitation is generally required compared to a newly set up tank which generally benefits from more.

Just be careful when you get the Kubotai, and try and add them at lights out. Consider having the CO2 off for a day to allow them to acclimatise to the tank water, and reduce their stress, then add the CO2 back slowly over a couple of days to allow them to get used to it, watching out for any surface gasping.

Also be warned that Kubotai do jump - I lost a few to start with from jumping, but your surface plants will certainly help with that.

EDIT: If you add some images of your tank showing a full tank shot, and also showing the level of surface movement, it may help with specific advice.
12232D71-2362-4DB8-ACC2-6ECCED827DA4.jpeg
 

Furgan

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Surface agitation is important for gaseous exchange, I would replace your spray bar with a lily pipe.
I had a Lilly pipe but upgraded filter and the pipers were a bigger size so it dosnt fit anymore! I always thought a spray bar was better
 

ceg4048

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From my understanding co2 reduces oxygen in the fish tank and then the plants exhale the oxygen at night! Adding oxygen via a bubbler when running co2 reduces the co2 performance- again please correct if I am wrong.
Hi,
Yes, sorry, as pointed out by wookii this is completely wrong. Oxygen, CO2, Nitrogen and other gases coexist in the water and none can affect the concentration of the other. Despite what many think, air bubbles do not actually add any oxygen by the mere fact that they are air bubbles. As bubbles break the surface of the water they distort the flat surface and increase the total surface area. It is this increase in surface area that facilitates additional movement of gases across the interface between the water and the air over the water. If the water has a higher concentration of Oxygen than does the air suspended over the water (by virtue of plant photosynthesis ejecting Oxygen into the water) then using bubbles will actually decrease the oxygen concentration level as well as decrease the CO2 concentration level. It is therefore counterproductive to use air bubbles during the day while photosynthesis is active. Air bubbles make much more sense at night when CO2 is being exhaled by both plants and fish. Plants do NOT exhale Oxygen at night.
With this in mind would I have enough oxygen available within the tank?
Based on the photo shown in your post it is not likely that you are adding that much Oxygen. Ferns are very slow growing plants and slow growing means that their rate of photosynthesis is also slow. The floating plants are exhaling most of their oxygen into the air above and only a relatively small amount into the water. The addition of faster growing plants will help in this situation as faster growth=> faster photosynthesis => consumes CO2 faster => produces Oxygen faster.

Cheers,
 

Furgan

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Hi,
Yes, sorry, as pointed out by wookii this is completely wrong. Oxygen, CO2, Nitrogen and other gases coexist in the water and none can affect the concentration of the other. Despite what many think, air bubbles do not actually add any oxygen by the mere fact that they are air bubbles. As bubbles break the surface of the water they distort the flat surface and increase the total surface area. It is this increase in surface area that facilitates additional movement of gases across the interface between the water and the air over the water. If the water has a higher concentration of Oxygen than does the air suspended over the water (by virtue of plant photosynthesis ejecting Oxygen into the water) then using bubbles will actually decrease the oxygen concentration level as well as decrease the CO2 concentration level. It is therefore counterproductive to use air bubbles during the day while photosynthesis is active. Air bubbles make much more sense at night when CO2 is being exhaled by both plants and fish. Plants do NOT exhale Oxygen at night.

Based on the photo shown in your post it is not likely that you are adding that much Oxygen. Ferns are very slow growing plants and slow growing means that their rate of photosynthesis is also slow. The floating plants are exhaling most of their oxygen into the air above and only a relatively small amount into the water. The addition of faster growing plants will help in this situation as faster growth=> faster photosynthesis => consumes CO2 faster => produces Oxygen faster.

Cheers,
Thank you Ceg, everyday is a school day.
I did have the substrate covered in the dwarf sag but pulled it all back as I was worried the corydoras would get trapped. I still have some at the back of the tank.

The tank has gone through many cycles over the years including a full dwarf hair grass with soil. It’s been a bit like triggers broom (only fools and horses reference).

The Java trident is new, and I enjoy it. The sand is for the corys. Just don’t know what to do else wise. I have some rocks that I took out last water change which are due to go back in, just was trying to find how I want to position the wood!

I’ll have a play with the outlet to create a better flow to increase surface movement. And look into other outlet options. I was going off the spray bar placement to one of your previous forum recommendations- but think this was designed for a heavier planted tank.
 

Driftless

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I had a Lilly pipe but upgraded filter and the pipers were a bigger size so it dosnt fit anymore! I always thought a spray bar was better
I wouldn't say one is better than the other but, again, gaseous exchanges are going to take place at the surface. If you are worried about the circulation lower in your tank watch the micro CO2 bubbles or micro-bubbles from something like a Twinstar sterilizer. I have a 257 liter tank that is 24 inches tall and I can see the micro-bubbles circulate throughout all of the layers of the tank from lily pipes.
 

Wookii

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Video of tank

sorry about background noise x2 french bulldogs!

As Clive has pointed out, your plant mass is very low, and they are slow growing plants, so unlikely to be contributing a great deal of oxygen to the tank themselves.

Looking at the video, the surface agitation appears to be almost zero, so I would definitely suggest more surface movement in any case, but it is even more a requirement given the low plant mass. I would start by angling the spray bar up towards the surface, say 45 degrees or so, so that you get a decent surface ripple - you may even need to raise the spray bar slightly. You may need to adjust your CO2 injection rate to compensate the increased off gassing - though I don't see a drop checker in your tank currently, so how are you verifying your CO2 levels?

You will still get the same/similar circulation pattern, and the random deflection of the water against the surface may actually give improved and random distribution in the tank - currently I can see the Cory's swimming against the flow at the sand level, but not much movement in the plant leaves up above.

That will force your floating plants against the front glass, but they will cope - floating plants can take quite a 'flow beating' in my experience.

Obviously the level of planting can be something of a 'design' choice, which is fine, but if that isn't the case, then I would suggest increasing the plant mass. The Cory's wont get tangled in plants, and will actually feel more secure from the increased cover - the bare tank bottom and relative lack of hiding places could actually cause them some stress. You can always keep a small area at the front clear for them to sift and target feed them.

Finally - and you probably already know this - but with quite a few Oto's in the tank you will need to make sure you regularly target feed them with some blanched cucumber or courgette, and algae wafers (if the Cory's leave them alone long enough for the Otos to get to them), at least 2-3 times a week.
 

dw1305

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Hi all,
I did have the substrate covered in the dwarf sag but pulled it all back as I was worried the corydoras would get trapped.
You don't need to worry. I would definitely increase the plant mass. Have a look at <"Corydoras breeder with planted tanks">. This is what Mark Allison said about plants
......... I’ve successfully bred 128 species of Corydoras, Scleromystax and Aspidoras. ...........

You have far more live plants in your tanks than I see in most cory breeders’ tanks. What’s the reason for that?

Initially I used a lot of Vallisneria torta for its long fl owing leaves. It made my C. aeneus species easy to spawn as the plant flowed well in the turbulent water and they would lay eggs freely on it.

This sort of evolved into a belief that although we see videos and pictures of typical Corydoras habitats that are sandy or leaf littered, the Corydoras must be laying on plants or some form of plant matter or roots and there must be plants somewhere upstream in the river whether it be overhanging trees or plants within the rivers and streams.

This set me off on a planted fish room whether it be moss, Guppy grass (Najas), Cryptocoryne or Java fern, and I found more species of Corydoras laid on plants rather than on the glass or spawning mops when provided. Eggs are also easier to remove from plants due to plant cells having a coating on.

The growing plants were also removing nitrites, nitrates and carbon dioxide and producing oxygen. In effect they were conditioning the water, making the quality last longer.
I've got Corydoras pygmaeus in this tank and they are absolutely fine. There is some sand at the rear of the tank, but even for a more bottom orientated Corydoras (like C. habrosus or C. panda) I'd still largely have leaf and plant cover on the substrate.

img_0126-jpg.jpg


but with quite a few Oto's in the tank you will need to make sure you regularly target feed them with some blanched cucumber or courgette, and algae wafers (if the Cory's leave them alone long enough for the Otos to get to them), at least 2-3 times a week.
I don't blanch the cucumber or courgette and I'd keep your "structural leaf litter" topped up. If the Otocinclus are spending a lot of time on the IAL leaf in the clip? It is a good indication that they aren't getting enough to eat.

cheers Darrel
 
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Wookii

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I don't blanch the cucumber or courgette

I've always blanched mine in a mug of boiling water for a few minutes, particularly the courgette, to soften the outside a bit, otherwise I find the Oto's seem to wait a day for it to soften up before chowing down on it.
 

dw1305

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Hi all,
otherwise I find the Oto's seem to wait a day for it to soften up before chowing down on it.
That is definitely true, "slightly slimy" is what they like. I should also have said Red (Capsicum) Pepper is a nutritious food that they like.

cheers Darrel
 
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Furgan

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Finally - and you probably already know this - but with quite a few Oto's in the tank you will need to make sure you regularly target feed them with some blanched cucumber or courgette, and algae wafers (if the Cory's leave them alone long enough for the Otos to get to them), at least 2-3 times a week.
The otos are getting well fed, Ive had them for a year now in the tank. mixture of bacter ae, algae wafters, courgette, rapashy soilent green, cyclops and daphnia.
 

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