CO2 (carbon dioxide) explained

[JustOneMore20]

Remembering what you learned about photosynthesis in biology really comes into play here. Wink Plants use light energy to take in carbon dioxide, which they then use to build plant material from by using the carbon. When you have low light, the available light slows down the growth of plants and the carbon dioxide from fish and bacterial respiration is enough for the plants. The more light you have, the more carbon dioxide required to maintain optimal plant growth. Once you are around the medium light category, the carbon dioxide from the fish and bacteria isn’t enough to satisfy the needs of the plants, because of the increased light. It is then that you should look into alternative sources for carbon, whether it be injecting carbon dioxide or using a carbon supplement. When you have excess light that the plants are unable to use, algae can take that opportunity to flourish, especially if the nutrients are in excess as well.

A carbon supplement that many aquarists use is Seachem’s Flourish Excel. It is not a fertilizer, but a carbon source. It seems to be almost as effective as injecting carbon dioxide when you have low-medium light over a tank. I would not say that it is equal to injecting carbon dioxide though, as this has not been my experience. I have also read on planted tank related forums that it has not proven to be as effective as carbon dioxide injection. On larger tanks, it can be an expensive alternative, as it is suggested that it be used every day or every other day. It is very good at getting rid of some types of algae and can even prevent some algaes. This is a better option for low-medium light, smaller tanks in my opinion.

Yeast Method
The yeast method is the cheapest way to inject carbon dioxide into an aquarium. Bottles are used with tubing and a diffuser. Inside the bottle, a mixture of sugar, yeast, and water are used. As the yeast ingests the sugar, fermentation occurs and carbon dioxide is released. The bottle must be airtight, with the airline sticking into it just about half an inch, so the gas can escape. On the other end of the airline is a diffuser. This can be a powerhead, airstone, or glass diffuser. I do not recommend using a glass diffuser with the yeast method, as usually there is not enough pressure to force the CO2 out of the ceramic disc of the glass diffuser and you risk having increased pressure in the bottle (could be messy). I have had good luck with powerheads (chop the bubbles up smaller) and limewood airstones (very fine bubbles). The smaller the bubbles, the longer they are in contact with the water. Here is a link to instructions and pictures: http://www.plantedtank.net/articles/DIY-Yeast-CO2/7/. The instructions use a drill to make a hole in the bottle top, but I have found that heating up a screwdriver (around the same diameter as your airline tubing or slightly smaller) up with a lighter or match will work just as well. Then you can use some pliers to pull the tubing through the hole. Many times, you do not even need silicone/sealant around the tubing, as the diameter of the screwdriver is smaller than the tubing and does not leave any space. Other methods of yeast CO2 injection are through store bought products. Hagen and Red Sea both make CO2 generators, which use yeast and sugar to produce CO2. These are going to be more expensive than making the system yourself.

Pressurized
Pressurized carbon dioxide is the most expensive method of getting carbon in the tank, but it is the most efficient. The yeast method does not provide a consistent flow of carbon dioxide and the levels fluctuate. Pressurized CO2 also can be setup and left alone until the tank needs refilling, while DIY CO2 (the yeast method) needs to have the mixture changed every 2-4 weeks to replenish the yeast and sugar. Finding an affordable CO2 system depends on how many aquariums you will be injecting CO2 into, what your budget is, and whether you want a package deal or can buy the pieces separately. The CO2 tank is going to be separate and you can find them locally or on the internet.

CO2 system parts:
The regulator is what you put onto the tank of carbon dioxide and regulates the flow. You can use any regulator, just be sure it will fit on your CO2 tank and can be used with tubing so that you can get the gas into the aquarium. Also, you want it to have low pressure and high pressure gauges. Many people stick to regulators marketed for aquariums. 2 of the more common brands are Milwaukee and JBJ. These can be bought from various places. I suggest doing a Google search for either brand (i.e. “Milwaukee regulator”) and finding the site with the best price. Another regulator type can be bought from a man named Rex Grigg. His website is http://www.bestaquariumregulator.com. He pieces together his own regulators, making them ready to use for aquariums. Azoo also makes a CO2 regulator and is sold at http://www.drsfostersmith.com. Along with the regulator, you can opt to have a solenoid, which when used with a timer can turn the CO2 on and off. When the solenoid is off, a valve is closed and the CO2 cannot get through. This is safe and while you may be worried about pressure building up in the CO2 tank, it may build up some pressure, but there is not risk of it “blowing up”.

Next is a needle valve. This is used to control the amount of carbon dioxide going into the tank. This can be used along with a bubble counter to get a bubble rate. Usually people start with 1-2 bubbles per second in the bubble counter and increase it as needed. Without a bubble counter, you can track your pH and KH (carbonate hardness) on a chart to see the amount of CO2 going into the tank. The needle valve is necessary to control the amount of carbon dioxide.

The next item needed is a check valve. You have probably seen the plastic check valves that are sold to be used with air pumps. Those should not be used with pressurized CO2, as they will break down with time and be useless. You want a brass check valve. These can be bought from various places on the internet. The check valve prevents water from somehow getting into the regulator and ruining it.

Next is tubing. You want to use carbon dioxide proof tubing. There will always be some CO2 loss, but you want to use tubing that will lose the least amount. Polyurethane tubing is used frequently with CO2 systems and loses very little CO2. If you cannot find this, silicone tubing can be used, but you’ll need to replace it occasionally because it will harden over time (and does lose a fair amount of CO2).

A diffusion method is also needed. This can be a powerhead, airstone, glass diffuser, or reactor. All of these work nicely. I suggest placing the airstone under the intake or output of your filter for better dispersion.

You can usually find a regulator, needle valve, and solenoid combo sold and often a check valve is included.

*A solenoid is optional if you plan to leave your CO2 on all the time. CO2 is not taken in at night (because of the need for light), so you are basically wasting the CO2, but it can help keep the level constant.
*A bubble counter is optional, but helpful.
*A pH controller can be used to set the amount of CO2 injected into the tank. It works with the solenoid and will turn the solenoid off when a certain pH is hit. CO2 is an acid so it lowers the pH. 1 full drop in pH (i.e. 7.6 to 6.6) is 30ppm of CO2 and that is said to be the goal for most aquarists with high light tanks. Therefore, that person could set their pH controller to 6.6 so that no more than 30ppm of CO2 would be injected.

Choosing which CO2 method is best for you can be a challenge at times. I suggest that with tanks 20g and larger where you have more than 3.5 watts per gallon, you should invest in pressurized CO2 or lower the light. On smaller tanks, even with high light, DIY CO2 can be effective. The larger the tank, the more CO2 needed, meaning more bottles are needed in the DIY setup. When you choose pressurized CO2, you then have to choose what size CO2 tank you should get. Generally, the bigger tank, the better you are. Bigger tanks will last longer between refills. A 5lb tank will be fine for a 20-30 gallon aquarium for quite a while though. CO2 tanks can be bought locally at welding shops or restaurant supply shops or online. One online source is http://www.aquariumplants.com . Prices vary depending on the size of the CO2 tank and the source.

I'll add some links later like it had before.

[fishboy689]

Wow, Thanks so much,
The first link you gave helped me so much..
Thanks

[fishboy689]

Much easier than buying a big expensive tank of Co2