How to Set Up an Aquarium CO2 System the Easy Way
When it comes to planted tanks, we always encourage beginners to start with easy, slow-growing plants that only need low lighting and an all-in-one fertilizer. Certain plants can be difficult to grow underwater. They may need more carbon dioxide (CO2) than what is naturally present in the air. Aquarists can inject CO2 gas directly into water using many methods. They have tried many types of equipment, scheduling and dosage amounts. Aquarium Co-Op has tested many of them, and this is our preferred method. It’s reliable and simple to use.
Can CO2 be used to get rid of algae? This is a common misconception. A healthy tank should have three components: lighting, fertilizer and carbon dioxide. CO2 is only one of the essential nutrients plants require to grow. Too much light and fertilizer is common among beginners. Adding CO2 to the aquarium can balance it. However, if a tank has high lighting and CO2 injection but, for example, too little fertilizer, then algae will appear because of the imbalance.
Let’s use a cookie recipe as an analogy. To make a larger batch of cookies (e.g. greater plant growth), you should add 5x the normal amount of flour (e.g. fertilizer), to your dough. If you increase the flour by 5x and then add 5x more chocolate chips (e.g. CO2) to the recipe, it will cause bad results (e.g. algae growth).
Does every aquarium plant require CO2 injection? All aquatic plants use CO2 for their basic building blocks. While some types, such as cryptocoryne, don’t need extra CO2, other plants like scarlett temple may benefit but won’t. The third group of plants, which includes Blyxa japonica and dwarf hairgrass and dwarf baby tears, is more demanding and requires CO2 to ensure success.
Materials for a CO2 System
This guide will focus on how to install the CO2 system, not lighting or fertilization. Gather the required equipment and tools to get you started.
1. Aquarium Co-Op CO2 regulator – What is a regulator? A regulator is a device that allows you to precisely control how much gas exits the CO2 cylinder tank and enters the aquarium water. What’s the difference between a single stage and a two-stage regulator? A one-stage regulator lowers the gas pressure in the cylinder in one step. However, a two-stage regulator lowers the pressure in two, which results in a more reliable and stable flow of CO2. A two-stage regulator also helps to prevent “end-of-tank dumps,” in which a nearly empty CO2 cylinder may dump out the rest of its gas in one go. Which CO2 system should I choose? While DIY systems are cheaper than pressurized systems, they don’t have the same stability as a CO2 system that uses a regulator and/or cylinder. DIY reactions can produce a lot of CO2 in the beginning, but then decrease over time. It can also make it difficult for a tank to be balanced due to inconsistent CO2 levels. Furthermore, the pressure is not as high, temperature can affect the reaction, and the overall process is time-consuming to maintain. A pressurized system is easy to set up and run for one to three decades before refilling the cylinder.
1. Aquarium Co-Op manifold block add-ons (optional) – With our regulator, you can install up to five extra manifold blocks add-ons to expand the system and run CO2 to multiple tanks.
1. CO2 cylinder tanks – Is it possible to use a CO2 paintball tank? These regulators work with standard cylinder tanks with the male thread size CGA320. I need a CO2 tank. We buy ours from local welding supply and home brewing stores. If your cylinder is empty, most stores offer CO2 refill service. Which CO2 cylinder size should I choose? High-tech aquariums injected with large amounts of CO2 will require you to refill your cylinder more often. However, for the average customer, we often suggest a 2.5-5 lb. cylinder for 20-gallon aquariums or smaller, a 5 lb. A 10 lb. cylinder is available for 25-to-40-gallon aquariums. cylinder for 55-gallon aquariums or larger. If you plan on using one regulator with five or six aquariums, then scale the cylinder size accordingly.
1. Airline tubing or CO2 tubing – Do I need to use special CO2 proof tubing or CO2 resistant tubing? We use the Aquarium Co-Op airline tubing (i.e., a flexible, black tubing made from food-grade PVC) on all of our aquariums and have not detected any perceptible loss of CO2. Our experience shows that special CO2 tubing costs more, is harder to bend, and is not as easily available.
1. Regular check valve or stainless-steel check valve (optional). Do I require a CO2 regulator? Check valves prevent water from flowing out of your aquarium and pouring onto the regulator. The bubble counter in the Aquarium Co-Op regulator comes with a built-in check valve, but you can install a second one as backup if desired. We have personally used the regular plastic check valves with CO2 systems at our fish store, warehouse, and homes, and they have not broken down. We also offer a stainless-steel version to increase durability, but CO2 can degrade plastic over time.
1. CO2 diffuser What type of CO2 diffuser should you get? A CO2 diffuser that is designed for aquariums operating at 40-50 PSI should work fine. What can I do to clean a CO2 diffuser that has become clogged with algae? Because diffusers can be made of different materials, follow the manufacturer’s cleaning instructions to use diluted bleach, vinegar, or other methods.
1. You can fill the bubble counter with regular tap water or mineral oil. This will allow you to see the CO2 entering the aquarium at an approximate rate. Mineral oil can be used in place of water, as the water will evaporate.
Timer for electrical outlets 1. Adjustable wrench of at least 1.25 inches width Scissors Spray bottle with water and a few drops Dawn dish soap
How to Install a Co2 System
Once you have all the equipment, we recommend you follow our detailed manual and video tutorial for step-by-step instructions. This diagram shows the connections between all parts of the CO2 system.
The regulator (B), screws onto the CO2 tank (A). The regulator (B), can be upgraded with optional manifold block add ons. The bubble counter (C), located on the regulator, is filled with liquid. An airline tubing attachment is made to the bubble counter’s lid. The airline tubing connects with the diffuser (D), which can be found at the bottom. The optional check valve, (E), is installed along with the airline tubing at the aquarium rim. The power adapter (G) connects to the regulator’s solenoid cable (F). The power adapter (G), plugs into the electrical outlet (H), which plugs into either a wall outlet, or power strip.
What if the CO2 bubbles emitted from the diffuser get into the aquarium’s water surface? This is normal. The key is to place your diffuser as low as possible in the aquarium. The bubbles released from the diffuser will imperceptibly shrink as they rise, and the CO2 gas is being absorbed in the water.
Place the diffuser at base of aquarium to allow the CO2 bubbles to disintegrate in the water for a longer period.
How much CO2 should you consume?
In the manual, we recommend tuning the regulator to approximately 1 bubble per second (i.e., the rate of CO2 bubbles flowing through the bubble counter) because we would rather start with a lighter amount of CO2 to keep the fish safe. That being said, CO2 dosing amounts are different for every tank, and the bubble rate is not a perfect form of measurement since each aquarium has different plant and fish stocking levels. Also, we personally do not use drop checkers to chase the “perfect” amount of 30 ppm of CO2, but instead we let nature and the plants tell us when they are happy.
When the plants photosynthesizing during the daytime, they consume carbon dioxide and produce oxygen (O2) and sugars as a byproduct.
If the plants have enough light and carbon dioxide, they can produce so much oxygen that it saturates the water and you can visibly see small bubbles released from their leaves. In our warehouse, we dial the CO2 level on our plant-holding aquariums until we consistently see this “pearling” effect. Plants are living things and it takes around 24 hours for any CO2 adjustment to have an effect. We like to wait three days before we make the next change.
When water is saturated with oxygen, aquatic plants can produce bubbles or “pearl”, which are visible to the naked eye.
When should I turn on and off the CO2 in my aquarium? As mentioned before, plants use CO2 when there is light to photosynthesize. But, this process changes at night to become the respiration cycle. In which plants take in oxygen and sugars, they release CO2. Therefore, we want to shut off the CO2 regulator when the aquarium light is off. To optimize CO2 use, set the regulator’s timer so that it turns on about 1-2 hours before the aquarium light comes on. The regulator will then turn off approximately 1 hour before the light goes out. You can also use a single timer to control the light and the regulator simultaneously.
Is CO2 dangerous for aquarium fish? It can be harmful for animals in large enough quantities if (1) CO2 causes the water pH to drop too quickly or (2) people try to be so efficient with the CO2 that they end up cutting off the oxygen that fish need to breathe. Some hobbyists attempt to minimize surface agitation, so that there is less gas exchange and less CO2 escaping the water. However, less gas exchange also means less oxygen will enter the water, which can cause your fish to struggle and gasp for air. Our recommendation is to increase both CO2 and O2 in the water by using an air stone (or other device that agitates the water surface) in conjunction with your pressurized CO2 system. Yes, you may have to increase your bubble rate a little to compensate for the slight loss of CO2, but having enough oxygen for your fish (and plants at night) is more important and can help lead to the pearling effect that is so desired by planted tank enthusiasts.
We wish you the best with your new pressurized carbon dioxide system. We hope you have lots of fun exploring high-tech plants. You can find more information about our CO2 regulator on the product page. There is a demo video and a manual.