# Does adding O2 benefit the planted aquarium?



## Jaap (25 Mar 2015)

Hi,

I was thinking if adding O2 will benefit the planted aquarium in direct or indirect ways. Any thoughts?

Thanks


----------



## Jose (25 Mar 2015)

Yes a lot. In many ways. Specially at night but during the day as well by making it possible to add more co2.


----------



## ian_m (25 Mar 2015)

Not really. Provided you have enough surface agitation O2 levels will be in equilibrium with the water, adding more will just gas it off.

Remember CO2 and O2 exist independently in the water, adding CO2 does not displace CO2. However monsterous levels of CO2 (over 30ppm) will overcome a fishes ability to excrete CO2, despite O2 being in the water and fish will have issues.

If worried about left over CO2 at night, put an airstone on it gas off the CO2 in minutes, probably won't affect O2 levels as no need to.


----------



## Mr. Teapot (25 Mar 2015)

Good oxygen levels = healthy tank. Just don't do anything silly like start adding pressurised O2.


----------



## Another Phil (25 Mar 2015)

Hi Jaap,
As all the folks above say and also even plants need oxygen when they're not photosynthesising, so surface agitation allows de-oxygenated water to pick up fresh from the air.

I often wonder if people with tall narrow tanks have more problems with low oxygen at night low down due to poor surface/volume ratio rather than CO2 problems.
cheers phil


----------



## EnderUK (26 Mar 2015)

Your livestock would probably face a real risk of Hypoxia if you began pumping o2 into the aquarium. Just run an airstone at night if you think it's needed.


----------



## Edvet (26 Mar 2015)

EnderUK said:


> Hypoxia if you began pumping o2 i


 Hypoxia through adding O2?? Hypoxia means suffocating , O2 shortage
Adding O2 in a full functioning planted tank shouldn't be neccesary, plenty O2 is produced.  Added O2 might be beneficial to filterbacteria especialy in low oxygen times aka night, or through using a "wet/dry phase"before the filter. I used a 150 cm long tube filled with bioballs as wet/dry filter before my sump.


----------



## Jose (26 Mar 2015)

I think the OP's question doesnt specify really. Adding O2 how? As a special measure e.g with an airstone? or maybe by just having surface ripple and good surface gas exchange?. Whichever way you do it is very important because:

1) You can add more CO2 and not suffocate fish.
2) Plants need it at night as well as bacteria 24/7.
3) Youll have a healthier environment over all. Amano does it at night.
4) Ive seen more pearling in the day when Ive added aeration at nigh (coincidence?, maybe).

Peoples views will differ because most people dont know how much o2 they have in their tank. Some may have a filter thats oxygenating the water while maintaining a tank without any surface movement and say its not important etc.


----------



## ian_m (26 Mar 2015)

Jose said:


> 1) You can add more CO2 and not suffocate fish.


Not true, mentioned already.



ian_m said:


> Remember CO2 and O2 exist independently in the water, adding CO2 does not displace CO2. However monsterous levels of CO2 (over 30ppm) will overcome a fishes ability to excrete CO2, despite O2 being in the water and fish will have issues.


----------



## Jose (26 Mar 2015)

ian_m said:


> Not true, mentioned already.



You can add more CO2 because at higher o2 levels fish can handle more co2.

So if you have 5 ppm O2 maybe you can only add 10 ppm of co2 until fish start gasping for air.. If you have 9 ppm o2 you might be able to add 50 ppm of CO2. Im not saying one displaces the other. This is about fish respiration.

Sorry if I didnt explain myself clear enough I normally dont.


----------



## Jose (26 Mar 2015)

This is the reason why people like Tom Barr say they can add up to 80 ppm of CO2 w/o fish problems whilst others can bearly add 20 ppm.


----------



## EnderUK (26 Mar 2015)

Edvet said:


> Hypoxia through adding O2?? Hypoxia means suffocating , O2 shortage


 
Sorry I meant Hyperoxia. In marine animals this increased oxygen in the water actually increases the CO2 in the blood. Biology isn't my strong point.



Jose said:


> You can add more CO2 because at higher o2 levels fish can handle more co2.


 
What I've read this is the other way around. You can add more O2 because your CO2 levels are higher.


----------



## Jose (26 Mar 2015)

EnderUK said:


> What I've read this is the other way around. You can add more O2 because your CO2 levels are higher.



Well this is way wrong.

Maybe if you said: You cshould add more O2 because your CO2 levels are higher, then it might make a bit more sense.


----------



## dw1305 (26 Mar 2015)

Hi all, 





Jose said:


> You can add more CO2 because at higher o2 levels fish can handle more co2. So if you have 5 ppm O2 maybe you can only add 10 ppm of co2 until fish start gasping for air.. If you have 9 ppm o2 you might be able to add 50 ppm of CO2. Im not saying one displaces the other. This is about fish respiration.


I'm a non CO2 user, because I can find quite enough ways of accidentally killing my fish, but I would be very careful going down this route, because it won't work for all fish.

There is an explanation here: <"CO2 and ....">.

cheers Darrel


----------



## Edvet (26 Mar 2015)

EnderUK said:


> increased oxygen in the water actually increases the CO2


 Not sure about this, only if it means no CO2 can get bound to the haemoglobin, but most gets transported as bicarbonate anyway. Never heard about this phenomena in fresh water.


----------



## Jose (26 Mar 2015)

dw1305 said:


> Hi all,
> Jose said: ↑
> You can add more CO2 because at higher o2 levels fish can handle more co2. So if you have 5 ppm O2 maybe you can only add 10 ppm of co2 until fish start gasping for air.. If you have 9 ppm o2 you might be able to add 50 ppm of CO2. Im not saying one displaces the other. This is about fish respiration.
> I'm a non CO2 user, because I can find quite enough ways of accidentally killing my fish, but I would be very careful going down this route, because it won't work for all fish.
> ...



Agree, and its specific for each fish. I think there are many more variables at play like the time the fish is exposed to CO2 etc. But there is a tendency. the more co2 you add the more o2 you need in the water. There is still going to be a limit for the co2 you can have. Thanks for the link Darrel!

The time a fish is exposed to x ppm of co2 is a very interesting factor. I think this is one of the reasons why aquascapers dont add CO2 at night. Ive been adding co2 in my tank in a continious manner for a few days non stop. CO2 levels are not climbing and should be lower than 30 ppm and more around 20ish. Fish at first are doing perfectly fine but after a few days they show some symptoms like gasping for air. I think their blood might be getting saturated after a few days? Does this make any sense? I really think CO2 is stable because pH isnt changing at all and I have good surface ripple. The ph is also higher than the ph at which they start gasping on day one, so CO2 levels shouldnt be high at all. O2 is constant as I try to keep surface agitation very stable.


----------



## ronaldmcdanger (26 Mar 2015)

recent facebook post by TGM...
https://www.facebook.com/1191095047...9109504790533/917801974921278/?type=1&theater


----------



## Mr. Teapot (26 Mar 2015)

ronaldmcdanger said:


> recent facebook post by TGM...
> https://www.facebook.com/1191095047...9109504790533/917801974921278/?type=1&theater



The product description made me laugh:
_Air sweeper provides deodorising and disinfecting effects to aeration activity when connected to the air pump and Pollen Glass for AIR. This equipment reduces the aquarium tank odour and *gives a mild fragrance around the aquarium tank*. Once its fragrance effect is lost, replace the Clean Beads inside the Air Sweeper with new ones. 

_


----------



## Rahms (26 Mar 2015)

ronaldmcdanger said:


> recent facebook post by TGM...
> https://www.facebook.com/1191095047...9109504790533/917801974921278/?type=1&theater



I'm sure the equipment is all very shiny and nice to look at, but all I can see is a re-invented airstone and some marketing


----------



## EnderUK (26 Mar 2015)

Hyperoxia in fish.

and


----------



## James O (26 Mar 2015)

Anything that releases fragrance into the air will release it into the water too.

But that's besides the point.  If your tank smells bad enough to require deodorant, something is wrong.....


----------



## Jaap (26 Mar 2015)

So the point is....good water agitation doesn't require an airstone...


----------



## Jose (26 Mar 2015)

Ive just read Darrels link. I must say I highly disagree with Clives point. He says that adding more o2 into the water doesnt really make fish withstand more co2. Well this is very easy to falsify. In most tanks with a wet and dry filter people are able to inject  really high levels of co2. Why? Because there is more o2 dissolved in them. the relationship co2/o2 is very important. We cant say 30 ppm is the maximum fish can handle because this depends on the o2 levels between many more things.

now this doesnt mean there isnt a limit. It just means that at higher o2 levels fish can live well in higher co2 levels. The levels vary with each fish, health condition etc etc.


----------



## ian_m (26 Mar 2015)

I think people are getting misled as O2 injection is often done in commercial fish farms. Done for one main reason, you can keep more fish per litre/cubic foot etc of water than without from typical air max of 0.5lb of fish per cuft to 0.75lb. Thus more fish to eat/sell for same tank.

Also done as tanks are generally small surface area wrt volume so won't absorb sufficient O2 from the air (air bubbling is only small O2 as bigger surface is better) and also O2 injection before filtration to improve filters.

O2 is expensive so is usually injected under pressure, best method is 20m deep hole with U tube in. You inject you O2 bubbly water down the tube were ar depth the hard to dissolve O2 dissolves. When is comes up is saturated ready to be diluted and given to fish. O2 is never bubbled in as expensive and in the short time is is in the water wont dissolve to make any difference.


----------



## Iain Sutherland (26 Mar 2015)

I just look at it simply...
fish, plants and bacteria need o2 when the lights are off so, as long as it isnt a pain, lifting the outlets before bed cant be a bad thing.  It also helps keep any surface scum at bay.  Certainly in my experience increasing agitation at night help keep things tidy but that is most likely because the tank isnt perfectly balanced in the first place.... ill take anything that helps counter act my blunders.


----------



## Jose (26 Mar 2015)

I just realized thet maybe I took Cegs words out of context. So I stand corrected by myself since its not very clear.


----------



## Edvet (27 Mar 2015)

ian_m said:


> air bubbling is only small O2 as bigger surface is better


It also improves circulation in tanks (especially in tanks with low circulation, (like in people's first tank with just a little LFS filter in it) and few plants), by circulating oxygen rich surfacewater with oxygen poor water from deeper layes.


----------



## ian_m (27 Mar 2015)

Here is the interesting article I found years ago about O2 usage in fish farming.
http://web.utk.edu/~rstrange/wfs556/html-content/17-oxygenation.html

An interesting read, no marketing overblown bumf, all aimed at maximising amount of fish grown in a closed system.


----------



## dw1305 (27 Mar 2015)

Hi all,





ian_m said:


> Here is the interesting article I found years ago about O2 usage in fish farming.
> http://web.utk.edu/~rstrange/wfs556/html-content/17-oxygenation.html


 I like this link as well. If you click on "contents" and "more" the whole course is available. <"I linked to it"> recently on the "PlanetCatfish" forum.

cheers Darrel


----------



## Jay1 (27 Mar 2015)

All I know is the o2 goes on at night, if the fish have had too much co2 and they recover, but from what I can tell switching it off at a non photoperiod i.e midnight is a good thing as plants give off o2 when resting as all plants need to rest or they melt don't they?
Plus it saves a load of money if co2 is just being vented to air if no lights are on right?
I did have someone suggest to inject pure oxygen with the co2 not sure how the dissloved o2 would compete with the co2 at the same time and I mean not an airstone. but via a o2 diffuser!


----------



## Another Phil (27 Mar 2015)

Hi Jay1,


Jay1 said:


> plants give off o2 when resting as all plants need to rest or they melt don't they?


Nope, plants give off O2 when they're photosynthesising, not resting, when they are resting (ie. at night/dark) they require oxygen intake like the vast majority of life.
cheers phil


----------



## Jose (27 Mar 2015)

So maybe if Jaap agrees we could just  say:
- how many of us add O2 at night?
- Do you see benefits?
- How is your surface ripple in the day?
- CO2 levels that you have (or think you have anyway)?

........I think this might help people decide?


----------



## dw1305 (27 Mar 2015)

Hi all, 





Jose said:


> So maybe if Jaap agrees we could just say:
> - how many of us add O2 at night?
> - Do you see benefits?
> - How is your surface ripple in the day?
> - CO2 levels that you have (or think you have anyway)?


I think people need to be very clear whether they are talking about low or high tech. 

*Low tech*.
In a low tech situation having a lot of flow and surface ripple increases the amount of CO2 in the water during the photoperiod, and decreases it during darkness when plants are respiring, but not photosynthesizing. The same principle applies to dissolved oxygen, during the photoperiod, when the water is fully saturated with oxygen, oxygen will out-gas to the atmosphere, and at night it will diffuse in. 

In low tech. with a large gas exchange surface levels of all dissolved gases will more closely follow atmospheric gas levels (dependent upon the solubility of each gas and the proportion within the atmosphere). Gases are constantly being replenished and out-gassed at the gas exchange surface via the diffusion gradients between water and air.

A lot of people on other forums don't understand this, which is why people say that you can't "_have much water turn over"_, or "_run an air stone"_ etc., in a planted tank, and that _"plants will kill fish at night by using up all the oxygen". _

*High tech.*
The difference here is that we are adding CO2. Carbon dioxide is a very soluble gas, but water (at equilibrium with atmospheric gas levels) doesn't contain much CO2, because CO2 is a very minor constituent of the atmosphere (~400 ppm CO2). 

When we add CO2 it will be lost at the gas exchange surface because there will be a steep diffusion gradient between atmospheric CO2 levels and the enhanced CO2 levels in the water. During the photosynthesis CO2 will often be the limiting nutrient, if we add more CO2 we can get higher levels of oxygen evolved, which we often see as "pearling"  where  the tank water is 100% saturated with dissolved oxygen. 

As soon as you stop adding CO2 its level will begin to decline back towards equilibrium with atmospheric levels, how quickly this happens will depend upon the gas exchange surface. If you don't have much gas exchange, or a large bioload levels may remain elevated. Levels of dissolved oxygen will follow the same pattern, they will decline as the bioload utilizes the dissolved oxygen. How low they fall will depend upon the gas exchange surface and the bioload.

I'm not an added CO2 user, but if I was I would want to reduce CO2 levels as rapidly as possible outside of the photo-period. For me in any situation maintaining dissolved oxygen levels near to saturation is a win-win situation.

Problems for fish can occur where levels of CO2 remain elevated, but dissolved oxygen levels fall.

cheers Darrel


----------



## Another Phil (27 Mar 2015)

dw1305 said:


> Problems for fish can occur where levels of CO2 remain elevated, but dissolved oxygen levels fall.


 
Hi Darrel,
My understanding is that that is more likely to occur in tall narrow tanks with little surface agitation as O2 can't diffuse to lower levels easily; true? or part of the Matrix?
I do know when I went to reverse-flow under-gravel via a canister filter with no surface agitation my fish weren't happy, and I had to use a"Y" splitter to divert 1/2 the flow direct to the tank to give surface agitation.
cheers phil


----------



## dw1305 (27 Mar 2015)

Hi all,





Another Phil said:


> My understanding is that that is more likely to occur in tall narrow tanks with little surface agitation as O2 can't diffuse to lower levels easily; true? or part of the Matrix?


Definitely true, in fact I think <"tank surface area to volume ratio"> is one of the most important factors in aeration. I also think that it is one of the reasons for the success of <"Tom's original bucket">.

It was the problems of maintaining large rheophilic fish in relatively deep tanks that led me to write <"aeration and dissolved oxygen ....">.

cheers Darrel


----------

