What is Co2 and how does it work

Hey guys,

could some one please explain in depth the uses of using Co2 in a fish tank. i dont understand anything about this and would like to know whats happening.

how much do they go for etc.?

thank u

 

Theo,

You have opened up a can of worms. I've asked this before, and there actually is not definite black and white answer... it's a very grey area.

To put it in a nutshell... EVERYTHING in life comes from Carbon. Carbon is the building blocks of life. This is junior highschool biology/science.

By adding Carbon Dioxide, you are in effect, adding carbon to the tank, which the plants utilize for growth. You will know from Primary school biology that the plants take in Carbon Dioxide, and through the process of photosynthesis, Oxygen is released. So I'm guessing that Photosynthesis breaks the carbon off the oxygen, releases the oxygen, and uses the carbon to grow!

How much to add depends on how many plants you have, how much the plants need CO2 and how much lighting you have. You can work out how much CO2 is in the tank based on a formula beween the Kh reading and the pH reading in your tank. Not sure how this works... don't have the formula. You can google it.

Price varies from R30.00 (DIY Yeast method) to R10k for pressurized systems. I would suggest you get into contact with people like henk (I think) and dolphin as to how to go about it properly. They seem to have the pressurized systems working very well.

Let me warn you though... playing around with CO2 has it's draw back too... I'm fiddling with putting CO2 in, and the imbalance between the CO2 and nutrients in the water for the plants to grow creates different kinds of algae blooms. It takes a lot of time and patience to find the balance.

Hope this helps?

 

Nice reply zoom, i too was baffled of the use of CO2 injectors...it would only be worth while having it in heavily planted tanks as well as tanks that have expensive plants...just my opinion...

 

Hi Jesse...

I have expensive, or difficult plants in my tank... but the CO2 has definately been a great addition to my tank. I am currently fighting a big of algae bloooms, but I will get it under control with the correct fertilization strategies. See my 4ft thread under the new member's section to see how the CO2 has helped me.

 

I was always under the impression that lighting was the main factor affecting plant growth?

 

it is matthew, as i've understood that without the proper lighting, CO2 injectors aren't as effective as they supposed to be...

 

Correct... the plants need the light in order to use the CO2 (photosynthesis)

Sometimes I feel I should have paid more attention in biology... this would have been so much easier then.

 

lol linxie...i slept in biology...i regret it now...

 

passed on Std grade.. just

it is easy to learn something u are interested in. you will catch on in no time

 

Lights+carbon+food= great plants

 

LOL JesseG

So true that Theo! Same with Geography, was never interested at school, but now I wish I paid more attention. Such is life ^^,

 

I think biology would have been a better choice than accounting... My crazy accounting skills dont seem to get me very far aquarium wise :/

 

I tend to disagree here a bit. Lighting is a VERY IMPORTANT factor, but not necessary the MAIN factor.

You can have the most amazing light, but without the necessary CO2, and fertz in the tank, you will land up with problems. Granted the plants will probably bloom very well.... the main concern here is that the algae will bloom even more. Algae blooms will eventually deprive the plants of all their nutrients, and they plants will start to die.

Let me expand Henks maths (light + CO2+ fertz = plant growth)... the CORRECT BALANCE between light/CO2/Fertz will give you absolutely stunning growh, with MINIMAL algae growths.

Do you know how many people are having algae problems? They complain that the algae is blooming and taking over their tank... but they aren't prepared to look at the lighting/CO2/Fertz because "the plants are growing perfectly fine, so it can't be that problem!"

I've recently discovered some algae going bossies in my tank at the moment, and I put it down to the cheal ferts I am using. I am in the prosess of trying to get hold of Prof. Dirks drops because I know his fertz is more beneficial than the stuff I am using.

 

Zoom I use the same ferts you do. I think the combo of those ferts and CO2 might be the algae problem.
I have about the same W/L lights then you and the algae bloomed once and not again. But with that said my plants do not grow like yours with the DIY CO2, but neither the algae so I guesse its good.

What mix did you use for the CO2 preportion wise?

 

HAHA... Now that's a trade secret...

Everyone says use 2 cups sugar to 1 tsp yeast. I have found that if I halve the yeast the mixture lasts longer, and produces the same output solid for about 2 weeks. After week three is slowls down exponentially. (If you use 1 tsp yeast, the mixture slows down very fast after week 1.5)

I add a "secret" ingredient too... but because you will eventually find out what that ingredient is via google... I'll let you in on it... 1 tsp bicarbonate of soda!

Another trick.. Put the bicarb, sugar and water into your 2litre bottle, and mix VERY WELL. Put the yeast into luke warm water with 1 tsp of sugar, stir very very well, and let this stand for 10 minutes. This activates ALL the yeast. Sometimes not all the yeast get's activated if you mix it all together.

 

Dont know how this reacts with the other stuff but does it not affect your PH

 

My pH was at 6.8 prior to introducing CO2. And for the past 3 weeks (since I started introducing CO2) has been at a constant 7.4. Was testing the pH twice a day when I started for 2 weeks.

 

You're pH went up?! How's that possible? Introducing CO2 acidifies the water as far as I know/read/heard.

 

Or it was 7.8 before. I just remember it being a somethin point eight

 

OK Guys,

I am glad to hear that you think that you should have concentrated more during biology.......

Well, light and carbon dioxide (CO2) are both essential for photosynthesis to occur. During photosynthesis the energy of light is used to convert CO2 to carbohydrates. Carbohydrates also contain hydrogen and this in actual fact comes from water! So we can write the following equation for the photosynthesis reaction:

6CO2 + 6H2O + light energy = C6H12O6 (glucose) + 6O2

The light energy is also not just any light, it needs to be of two different wavelength bands, the one is in the blue light area around 400 nanometers and the second is in the red light area around 650-700 nanometers. This is also the reason why plants are green. When light shines on plants they absorb the blue and red colour and some of the yellow, and they reflect the green colour. Which is why plants then look green!

Bottom line is that in order to get plants to grow you cannot just use any old light, you need to concentrate on the specific wavelengths of the light that the lights emit. This is why lights with an increased red and blue spectrum give good plant growth. And it cannot be only blue or only red, it needs to be a combination of both!

However, the CO2 thing is also heavily influenced by the so-called carbonate hardness of your water. Carbonate hardness and pH are in a balance with free CO2 in the water. If you have a low carbonate hardness, which is what we have in most places in South Africa, and you have a pH below 7 there is actually enough free CO2 to feed your plants and the whole CO2 fertilization thing is completely unnecessary. I do not use it and still get very good growth even with the most fancy of plants which are said to only grow with CO2 addition, things like Limnophila aromatica and Pogostemon stellatus.

When you add CO2 to the water by injection, it reacts with the water and forms carbonic acid which in turn reduces the pH. It is also when you do not regulate CO2 injection properly with a decent CO2 regulator that regulates the CO2 by keeping the pH constant during this process that you have all sorts of problems in your tank. What happens is that during the day, when your lights are on the CO2 gets absorbed from the water by the plants. Once the lights are off at night, the plants cannot use the CO2 any more and unless you regulate the CO2, the levels go up and up causing the pH to gone down more and more. This sort of instability causes incredible imbalances in an aquarium which are highly detrimental for your fish and also for your plants (I mean one minute you are in water and the next you are in an acid bath) and this sort of imbalance is exactly the situation that algae will thrive on. So, as far as I am concerned all this fiddling with CO2 unless properly regulated with a pH electrode is a ticket for disaster, exactly what you are telling us, Zoom!

So, light and CO2 are essential for photosynthesis. Once the plant produces the glucose, it can use this to give the energy to grow and it will then use all the other components in a plant fertilizer to built up stems, leaves, roots and possibly seeds.

So, you see, the biochemistry professor can give you a few lessons in biology if you did not concentrate at school, but these are very complicated processes, I have simplified massively and you need to be very careful not to get it wrong because you do not understand the basic biology behind it.

Kind regards,

Dirk