air bubbles with c02 system

[theantmac]

hi,

im just after a little bit of help as recently ive started to use a DIY c02 system and i also i have heard that air bubbles will take the c02 out of the water. should i remove my air stone from the tank? is it pointless having both the c02 system and the airstone in the tank??? they are at opposite ends of the tank aswell

ant

[JLL]

hi,

im just after a little bit of help as recently ive started to use a DIY c02 system and i also i have heard that air bubbles will take the c02 out of the water. should i remove my air stone from the tank? is it pointless having both the c02 system and the airstone in the tank??? they are at opposite ends of the tank aswell

ant

Not at all. You should leave the airstone in. The bubbles coming out of the DIY system will be lost to the system if they reach the surface before dissolving into the water so that should be your only concern for losing CO2. You still need oxygen in the water so the airstone will still be doing its job whilst the CO2 system is only putting CO2 into the water.

[AzFish]

Basically any excessive agitation of the water surface or bubbling of air through the water will cause the CO2 to escape into the atmosphere, just about as quickly as you can add it.

Cheers,

Az

[CThompson]

CO2 and O2 will exist side by side and have no impact on each other.

If you have an established Planted tank, plants are the most efficient oxygenators that you can use. That is, a tank with an airstone can only put so much O2 into the water. Plants can put more O2 into the water, to the point the water will become 100 % saturated at which point you will start to see air bubbles stream from plant leaves to the water’s surface or fine-leafed leaves may have the pure bubble of O2 stuck to them.

In a Planted tank, plants can put so much O2 into the water that an airstone is pointless. Move over, it will cause the CO2 in the water to come in contact with the water’s surface where it will be lost to the atmosphere. Though CO2 and O2 can coexist, CO2 is much more volatile and will be lost to the tank (= to the plants) if it gets to the surface. That is, the upward current that the air bubbles will create will cause the hard earned (and paid for) CO2 to be carried to the surface and lost.

In a “proper” Planted tank, the emphasis is on plants and fish are secondary. In essence, that means there won’t be enough fish to need mechanical aeration.

A planted tank is all about balance, and the tank itself can go through some huge chemical swings, day to night with pH and CO2 and O2. With the right balance, mechanical aeration is not needed. This I think is not well understood.

[JLL]

I would still maintain that having an airstone at the other end of the tank for a failsafe if nothing else is warranted.

If you do not have enough plants, fast photosynthesisers, correct nutrient balance, enough light, long enough photoperiod or too many fish (not to mention countless other parameters) then you can easily enough end up with a problem. Also, both your fish and plants respire (use oxygen) during the night and plants do not add oxygen at this time.

Basically if you are like 99% of people with a 'planted' (not necessarily proper) tank that just want plants and fish in a tank and for them to look good then you are probably not worrying about all of the variables.

Whilst I mostly agree with Mr Thompson (I have just parroted much of what he said), it is advice for the person looking to control and understand the environment that they are manipulating which he pretty much says anyway. However, some mechanical agitation is beneficial (from filters usually) as CO2 generally originates from a single point and concentration gradient alone will not always lead to good distribution throughout a large tank in think plantings, especially if the CO2 point is at the end of the tank. Also plants can release gaseous oxygen into the water prior to saturation if the rate of release is greater than the rate which oxygen is dissolved into the water (think about what happens with an airstone, just at a massively smaller rate). Of course this means that you are far more likely to see oxygen coming from plants at or near saturation as the rate that oxygen dissolves is very low at these times.

[theantmac]

thanks alot for the help. ive come to the conclusion that i am going to turn my airstone down using a valve, and this way there should be both enough oxygen for the fish to survive and there shouldnt be too much surface agitation as for the c02 to evaporate out of the water. well this is the plan anyway as it makes sense to me. any other advice?

[CThompson]

For a full on co2 injected plant tank, an air stone is not wanted. Even turned down there will all the vertical current needed to force the co2 out of the tank.

Don’t forget air gets into a tank via the tank’s surface, and most people have so many fish in their tank that mechanical aeration is mandatory. Most people don’t have the experience to understand when few fish = no additional aeration required. I don't recall what fish or their numbers you have.

Do you run a risk to the fish to have no air stone? Yes. But until you try it you will not know if you need the extra assistance. If you need mechanical aeration AND you want a co2 injected PLANTED tank then I’d suggest that your first step is to reduce fish numbers NOT add aeration. I ran a 400-500 litre planted tank with automated co2 that was full of plants and lots of fish with NO aeration for years. There is a lot of balance to achieve and to have an air stone you are making this balance difficult to achieve – why make it harder?

A "real" co2 injected plant tank has few fish and no need for an air stone. If you feel that you have enough fish that an air stone is warranted, then you will in most likelihood be creating a "limiting factor" (co2) for plant growth. This can have large knock-on detriments.

Google "Liebig minimum theory of plant growth".

Absolutely the tank needs water movement but it wants to be in a horizontal direction not vertical.

I fully agree with Mr. JLL in that this will be greatly dictated by whether or not this is a "PLANTED" tank or a tank with plants in it. IF it is a PLANTED tank then an air stone is anathema to the system you are trying to achieve.

[JLL]

theantmac, I think we are just trying to flex our botanical mussle here Everyone loves a peeing contest from time to time, me included.

If you are to use the Law of the Minumum then you must consider ALL plant limiting factors and not just CO2. It is an exceptionally simple concept, basically, plant growth will be limited by the factor in the shortest supply relative to the plants needs.

But, if we read between the lines a little here then you are not a planted tank enthusiast, just someone that asked a simple question in relation to your new DIY setup. That being the case, I don't think that dissolved CO2 volatilisation (loss to the air) should be too big a worry in your situation.

Do a bit of reading on planted tank setups online and go on from there. Someone like Craig has a lot of great advice, but not everyone is so accurate. I remember one LFS trying to tell me that phosphorous must never be present in a planted tank and sources of it eliminated even though plants cannot live without it.

There is a heap to learn but if you are keeping a lot of fish in the tank then remember that you generally kill plants quite slowly when compared with fish. This gives you a chance to alter the conditions slowly to favour plants and help their recovery but you are not always given the same luxury for maintaining your fish. It is far easier to quickly kill fish than plants.

[theantmac]

umm... ok ill begin by saying again thanks in advance for all the advice i know my basics about plants and names, water parameters etc. but i am still learning so all this advice is great and no your right i am not an expert . the tank is heavily planted and with no experience in aquascaping i cant fit any more plants in there but my amazon swordplants and java ferns are allways multiplying in numbers as they do so i will be planting the new ones as i have done in the past. the tank has been running without c02 for around 6 months to a year. there is some cross tank current coming from my filter (800lph) and the fish are 8xalbino longfin bristlenose, 5xalbino tinfoil barbs and 8xsiamese algae eaters. thats it from memory and i am trying to get rid of the barbs as they eAt the plants .

heres a pic of the tank the diffuser is on the right and you can see the plants lol im doing my best to make it a professional planted setup but so far this doesnt show in my plants im hopeing the c02 will change that.

pic

http://i624.photobucket.com/albums/tt324/antmac/P1010006.jpg

i understand that no one wants to tell me how to kill my fish but i do have one question. if we forget about the fish, does having a small amount of bubbles remove the c02 from the water? im sorry for going back to this except i dont understand if it removes some or all of the c02 so if you could explain that itd be great neways thx in advance again

[theantmac]

and also, the plants are amazon swords, anubius, potted crypts and java ferns thats all.. do these require much c02? if need be i can add another cannister to the tank to create more c02. oh and i can also turn off the air pump alltogether i think, as the tank is definately NOT overcrowded with fish i dont think

[JLL]

In short, yes. The amount that you disturb the water will increase the gas exchange rate with the atmosphere and because you are trying to keep a higher level of co2 in the water than the air the result will some loss of co2 to the air. Your filter outlet low in the tank and pointing up is also increasing this effect.

With that amount and type of plants I would not worry so much about more co2 at the moment. Make sure that you have enough light and your other nutrients are being catered for first.

[theantmac]

since ive added my c02 system the plants are looking slightly better allready. i also forgot to add that i use flourish liquid fertilizer and JBL plant balls that go into the gravel for nutrients. i will point the filter outlet downwards since you said thats the way to go and i have since removed the airstone with no detrimental effects to the fish so far. so hopefully that will also stop the c02 from leaving the water. and i am also going to add the other c02 cannister to the water today i have decided. hopefully this will create an ideal environment for the plants as i have read that c02 is vital for their optimum growth and healthy green colour. i am also planning on getting some more exotic types of plants in the future but will have to wait and see as to what i will get.

lighting on the tank is a double fluorescent light and i know this isnt the best (halides and t3 or t5 would be better) but im assuming its enough for these types of plants especially since the tank is only 20" tall. in the picture the tank looks very dark for some reason but i think it gets enough light as the light is left on for 7 hours per day. feel free to correct me if im wrong.

[JLL]

You will still lose CO2 if the plants do not use it quickly enough which is likely the case in your setup at the moment.

Remember what Craig mentioned about limiting factors. If you are using just a standard T8 fluro then light will most probably become the limiting factor (it may well be already) and any other additions of CO2 etc will be a waste. I would also suggest that a 7 hour photoperiod is a little too short if you are after vigourous plant growth.

[CThompson]

Personally I was not in a "peeing contest" For myself, I had no personal issues with what you said JLL. The point I was trying to get across was that there is a difference between a tank with plants in it and a planted tank. And a PLANTED tank does not want an air stone - this I feel strongly about. A PLANTED tank wants nothing that will encourage a water flow that will cause upward movement so CO2 will be taken to the surface, and I know you agree with this. That means and air stone or a filter return outlet. The PLANTED tank absolutely wants water movement but one should not plan on utilising anything that causes this movement to be vertical.

As JLL says, there is a lot of misinformation out there and a PLANTED tank is no exception. The difference is that to have a successful tank you will need more information, and more knowledge with subtle differences. Basically, to be a successful PLANTED tank owner you need to be a better aquatist.

It may be easier to kill fish, but it is harder to have a truly successful PLANTED tank (it certainly takes more work - especially if you get into high requirement and/or bunch plants).

Do read up on the Liebig Minimum theory. I used to make my own aquatic fertilisers and applying this theory was more fact than theory as far as I'm concerned.

and also, the plants are amazon swords, anubius, potted crypts and java ferns thats all.. do these require much c02?

The sort of plants you have are all low nutrient requirement plants. You could probably/possibly get by without CO2 injection, BUT they will assuredly do better with extra CO2 (because of the Liebig Minimum Theory).

From you photo; your tank has not got many plants and looking at it I would not call it a PLANTED tank. But then, what makes a "PLANTED" tank? CO2 injection is certainly putting in this direction.

does having a small amount of bubbles remove the c02 from the water? im sorry for going back to this except i dont understand if it removes some or all of the c02 so if you could explain that itd be great neways thx in advance again

There is absolutely nothing wrong with asking again. I will make my answer as simple as I can, it is not a difficult concept - don't over think it;

Air bubbles will NOT remove CO2 from your tank. CO2 will be removed from the tank if and when it comes into contact with the surface. Anything that promotes a vertical water movement will cause CO2 to come in contact with the surface. CO2 is hard to keep in a tank. Why encourage it to leave?

To put it another way; If you have an attractive person in a room with you and you want them to stay, do you leave the door open with flashing neon lights saying "this way out" then push them towards the exit. Or do you close and lock the door and do your best to hide the key?

If you don't need to run air for fish, why run it? Don't think; "I have an aquarium therefore I need an air stone". The only benefit it could bring in this case (where the extra 02 is not needed) is to encourage suspended matter to remain suspended so the filter can get to it.

In a FISH, fish tank water movement in any direction is good.

In the case of a PLANTED tank, the greater evil is to let encourage CO2 to get to the surface.

Aquarium keeping is an information hobby – keeping a PLANTED tank requires more knowledge = more information.

lighting on the tank is a double fluorescent light and i know this isnt the best (halides and t3 or t5 would be better) but im assuming its enough for these types of plants especially since the tank is only 20" tall. in the picture the tank looks very dark for some reason but i think it gets enough light as the light is left on for 7 hours per day. feel free to correct me if im wrong.

Any tank greater than 20" will require better lighting. So, in my opinion your lighting is fine. Your plants as mentioned are low requirement plants. However, you don't mention what the bulbs are. Plants utilise red and blue light (in near equal proportions) to grow, and grow in the correct proportions. The best tube I came across is a NEC Triphosphor Fluorescent (http://www.alpinelighting.com.au/services.htm). Has a great red and blue spikes with some green (which the plants don't use but it makes them look good). These are cheaper than the special lights sold in aquariums for plants and last nearly double the time. Don't get another brand, it must be NEC.

[Maskedman]

This may be an old thread but for anyone reading it that has the same issues. Leave the airstone in the tank but set it on a timer so that it only comes on at night. Plants release oxygen during the day but at night they release CO2. That's bad news for the DIY CO2 tank. Because we can't just switch our reactor off, we are pumping CO2 in at night while the plants are also producing it. That gives us higher CO2 levels at night. If those levels get too high it can be lethal for the fish. With fluctuating CO2 levels comes the associated PH swings, (as Co2 levels increase PH will go down).Check your PH half hour before your lights go off & then the next day half hour before the lights come on & you will see what I mean. Your PH will be lower in the morning.

Put that airstone on a timer to switch on at night & it will help keep the CO2 & PH fluctuations to a minimum by adding some upward current to help dissipate the extra CO2 into the atmosphere. Do it regardless of wether your fish show any signs of distress or not.

[theantmac]

hey maskedman its not that old- thanks for the post. atm i have the air pump on with really really small amounts of bubbles because my fish are showing signs of stress e.g increased gill movement etc. but the main thing i am trying to achieve in this tank is increased plant growth NOT fish. do plants need c02 at night? if not ill set the airstone on a timer like you said.

i have also bought 2 NEC aqualux 4ft tubes for my tank and am picking them up tomorrow thx to you guys. in the mean time my java fern has completely taken off and so have the crypts theyre both looking very very healthy. the amazon swords arent doing too badly also. the only thing is my anubius plants arent doing too well or looking too good for some reason. they arent dieing but they just havent been doing as good as the others. e.g they have holes in the leaves and arent growing quickly. maybe they arenht meant to grow fast or maybe i am still doing something wrong lol.....

these planted tanks are alot of effort lol

[JLL]

Nup, the plants will not use CO2 in the night unless they are CAM plants (like bromeliads) which your plants are not.

Anubias do not really grow quickly so don't worry about that. The holes could be browsing or nutrient deficiency depending on where the holes appear, new or old leaves, and the look/size of the holes. Possibly potassium but unfortunately I am better at determining deficiencies in terrestial plants.

While your tank is getting up to speed plant wise maybe you could try getting a couple of weedy plants temporarily to increase the plant presence while your desirables grow up.

[theantmac]

thx for all the help. the plant tank is going great so far everything is looking better and better and i can even see what you said about the tiny air bubbles coming off the leaves of the plants from over saturation of oxygen in the tank. it looks quite nice actually and yes i will think about adding even more plants to the mix soon. will post up a pic for you to compare in a few months time when the plants have grown more and gotten even healthier fingers crossed

[Maskedman]

Good to see your getting a grip on it all. CO2 is just a waste product for the plant at night. Anubius in general are a slow growing spieces that doesn't like light to be too bright. The holes are probably in the middle of the leaves if they are like mine & it is caused by plecs & brislenoses. If it is the fish the holes will have nice green edges. If it's some kind of deficency the holes will have brown or yellow edges.

If you want to remove the fish you could get your CO2 up to around 35ppm (lethal to fish) & your plants should start to boom along.