How to Set Up an Aquarium CO2 System the Easy Way
We encourage newbies to plant tanks with slow-growing plants. They only require low light and an all-in one fertilizer. Some plants may be more difficult to grow under water and will require additional carbon dioxide (CO2) and high lighting. 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 tried many and created this guide to help you choose the most reliable and simple method.
Can CO2 be used to get rid of algae? This is a common misconception. A healthy planted tank must have three components in balance – lighting, fertilizer, and carbon dioxide. CO2 is just one of the primary nutrients that plants need to grow. Too much light and fertilizer is common among beginners. Adding CO2 to the aquarium can balance it. Algae can develop if there is too much fertilizer or high lighting in a tank.
Let’s use a cookie recipe as an analogy. You can increase the flour by adding 5x more (e.g. fertilizer) to the dough. Then you will need to multiply the other ingredients (e.g. lighting and CO2) by 5x. This will produce a larger batch of cookies, which will lead to greater plant growth. You can make a bad cookie if you only add 5x as much flour to your recipe.
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. To get started, gather the necessary equipment and tools:
1. Aquarium Co-Op CO2 regulator What’s a regulator? It is a device that controls how much CO2 exits the CO2 cylinder tank into 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 tank – Can I use a CO2 paintball cylinder? No, the Aquarium Co-Op regulator is not intended for use with paintball tanks. They are compatible with standard cylinder tank sizes that have the male thread CGA320. Where do I get a CO2 Cylinder? We prefer to buy ours at local home brewing supply shops and welding supply shops. Usually, they also offer CO2 refill services if you bring back your cylinder when it’s empty. Which size CO2 cylinder should you get? For high-tech planted aquariums that use high levels of CO2, it is recommended to get the largest size cylinder possible. This will allow you to not need to refill the cylinder as often. For the average customer, however, we recommend a 2.5-5lb. cylinder for 20-gallon aquariums or smaller, a 5 lb. A 10 lb. cylinder is available for 25-to-40-gallon aquariums. cylinder for aquariums up to 55-gallon. 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. In our experience, special CO2 tubing is more expensive, harder to bend, and not as readily available.
1. Regular check valve, stainless steel check valve (optional). Do you need a check valve to protect my CO2 system from water escaping the tank and pouring over the regulator after it is turned off? The Aquarium Cooperative regulator has a built in check valve. However, you can also add another one to provide additional protection. 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. However, plastic can be degraded by CO2 over time so we offer stainless steel versions for better durability.
1. CO2 diffuser Which CO2 diffuser type should I choose? All CO2 diffusers designed for aquariums should operate at around 40-50 psi. – How do I clean a CO2 diffuser if it becomes clogged? Diffusers must be cleaned or replaced at some point because of algae buildup. Different materials can make diffusers, so follow the manufacturer’s cleaning instructions. Use diluted bleach, vinegar, and 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. However, the water will evaporate over time, so mineral oil can be used instead so you never have to refill the bubble counter.
An electrical outlet timer Adjustable wrench with at least 1.25-inch width 2. Scissors 3. Spray bottle with water and a few drops Dawn dish soap
How to Install a CO2 system
After you have everything you need, you can follow our video tutorial and detailed manual for step-by-step instructions. This high-level diagram will help you see the whole CO2 system.
The regulator (B), which screws onto the CO2 tube (A), is shown in Figure 1. The regulator (B), can be upgraded with optional manifold block add ons. – The bubble counter (C) on the regulator is filled with liquid, and airline tubing is attached to the lid of the bubble counter. The airline tubing connects directly to the diffuser, which is located at the bottom. – The optional check valve (E) is installed in line with the airline tubing near the aquarium rim. The regulator’s solenoid vale cable (F), is connected to the adapter (G). – The power adapter (G) plugs into the electrical outlet timer (H), which plugs into a wall outlet or power strip.
Does it make a difference if CO2 bubbles from your diffuser reach the water surface? It is perfectly normal. It is important to position your diffuser as low in the aquarium as possible. 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 to Dose
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.
The plants photosynthesise during daylight hours and consume carbon dioxide. They also produce oxygen (O2), and sugars.
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. It takes plants 24 hours to adjust the CO2 level. Therefore, we wait three days to make any changes to the system.
Aquatic plants “pearl” or visibly produce bubbles when the water is saturated with oxygen.
When should I turn on and off the CO2 in my aquarium? As mentioned before, plants use CO2 when there is light to photosynthesize. However, the process reverses at night and becomes the respiration cycle, in which plants consume oxygen and sugars and 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. Hobbyists may try to reduce surface agitation in order to limit gas exchange and CO2 escape from 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. We recommend increasing both O2 and CO2 in the water using an airstone (or any other device that agitates water) along with your pressurized carbon dioxide 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.
Best of luck with your new pressurized CO2 system and we hope you have fun exploring the world of high tech plants. You can find more information about our CO2 regulator on the product page. There is a demo video and a manual.