8 Best Aquarium CO2 Regulators Reviews – Comparison & In-Depth Buyer’s Guide

If you want to create a successful, thriving environment for your fish, corals, live rocks, invertebrates, and plants, you need to monitor your CO2 levels consistently.

Time has proven that aquariums supplemented with an external carbon dioxide source will grow much faster than tanks without supplemented CO2.

However, getting started supplementing the CO2 levels in your tank requires a significant undertaking. Understanding the different types of equipment used can be a frustrating experience, even for advanced aquarists.

What Are The Best CO2 Regulators For Aquariums?

To get started, we’re breaking down some of the most common CO2 regulators to determine which are the best CO2 regulators for aquariums, both freshwater and saltwater.

If you’re new, start here. Then, pick your equipment and work your way through the rest of the guide. If you have any questions, feel free to reach out to us or leave a comment below.

CO2 Regulator Benefits -- Why They’re Required

If you aren’t sold on why you should be using a CO2 regulator in your aquarium, we’ve included a few key benefits that will help you understand why regulators and CO2 are so critical to tanks.

Benefit #1 - Promotes Healthy Plants

For your plants and fish to appropriately co-exist, you need to give them both the environment they prefer.

For plants, they need CO2 to properly go through their photosynthesis and convert waste, ammonia, and other harmful byproducts into usable oxygen. Giving your plants the environment they need to thrive means your fish will get more of the plant’s byproducts to feast upon.

With the right amount of CO2, you create a healthy ecosystem that supports both your fish and your plants and lets them live out natural lifecycles. Without maintaining those CO2 levels, your plants begin to suffer, which causes your fish to suffer, too.

Benefit #2 - Promotes Healthy Fish

Fish, while living and breathing, are going to excrete carbon dioxide. Excessive levels of carbon dioxide can become toxic. While your plants can utilize what’s being expelled from your fish, your plants may not have enough available.

Without having a system in place to correctly measure the CO2 levels in your tank, you’re going to be guessing. That means you’re going to end up with dead plants, followed shortly after by dead fish. Nobody wants dead fish.

Benefit #3 - Prevents Algae Growth

Algae growth is one of the biggest threats your tank will face. Algae affect your tank by creating unhealthy conditions that will stifle the oxygen levels your fish and plants require to thrive. It can also help harmful bacteria breed which can affect your fish, causing disease or illness that quickly spreads.

Studies have shown that low levels of CO2 gas allow algae to bloom and create ammonia. Ammonia is a waste byproduct that, when left out of control, can quickly create hazardous scenarios in your aquarium.

Installing a CO2 regulator with a gauge, bubble counter, and other meters to consistently measure the amount of CO2 gas in your tank can help stave off these potential problems.

How Does A CO2 Regulator Work?

If you have built a planted aquarium, adding a CO2 regulator and system is a relatively easy concept to wrap your head around. CO2 from a cartridge or canister is transferred through a CO2 regulator to help lower its initial pressure.

High-pressure CO2 will be a blast of air into your tank, while lower pressures can be converted into small bubbles that carry the gas throughout your aquascape. Converting the CO2 gas into a usable stream of tiny bubbles happens through other equipment.

Smaller bubbles are required in order for the gas to dissolve into the water. As the CO2 gas dissolves into your water, your plants will begin to synthesize the proper nutrients they need to sustain themselves. This is called photosynthesis.

Pressurized CO2 utilizes a regulator so you can adjust the pressure coming out of the canister at a rate of flow that will not harm your tank. Advanced regulators use electronics to help time the release of CO2 gas and control the amount that is flowing through a solenoid or check valve.

The timer on these systems helps prevent excess gas from building up or using too much of your CO2 gas at one time. For instance, you can disable your CO2 system at night when plants photosynthesize nutrients at a slower rate than they do during the daytime.

Disabling your system at night helps you save CO2 gas, which reduces your expenses. As the timer ticks over, a solenoid valve will be activated which releases gas into your regulator. The valve will only release CO2 gas when the timer activates the solenoid and gas passes to your regulator.

If you aren’t using a CO2 cartridge or canister, you will need to utilize a yeast-based system to release CO2 gas in your tank. Yeast-based systems cost more money than CO2 cartridges over the long run. With a cartridge, you can maintain stable levels while yeast creates variable levels.

When you’re using a cartridge-based system, you may only need to replace the canister or cartridge once every 6 to 12 months. Yeast will need to be monitored on a routine basis. While it is more expensive upfront, a canister-based system is cheaper to maintain over time.

CO2 Regulators In Planted Aquariums

Now that you know a CO2 regulator is used to control the level of CO2 gas being dispersed into your tank, the next step is understanding why your aquarium needs it. Regulators operate by attaching a CO2 cartridge and allowing a set amount of gas to escape into the water.

CO2 regulators are all built using the same set of principles. A high-pressure valve and a low-pressure valve help regulate the amount of gas coming out. The regulators utilize a set of gauges to measure the high and low pressure.

Regulators will also use a check valve, a needle valve, and a solenoid valve to help control the amount of gas being produced. Some may have a built-in counter to measure the bubbles being produced while others will not.

Your high-pressure gauge helps determine the level of gas left inside of your canister. The indicator tells you, specifically, how much liquid CO2 is left inside of the cartridge. You know it is time to replace the cartridge when your high-pressure gauge reads at zero.

Your low-pressure gauge, on the other hand, tells you how much CO2 gas is being emitted into your tank. Your low-pressure gauge helps you dial in the amount of gas that’s being released into your tank. It enables you to determine the maximum pressure that you want to be released from the canister.

Your bubble counter helps you determine how much CO2 is flowing into your tank based on the number of bubbles being released. Bubble counters typically measure the number of bubbles per second. This gives you a visual you can look at to quickly see what you need to adjust.

Your needle valve helps dial in the amount of CO2 gas being released from the cartridge into your water. The needle valve is how you control the actual number of bubbles being released at tiny increments. The quality of your regulator determines how accurately the needle valve works.

CO2 Regulator Essentials

Once you have chosen a regulator that’s well-suited to your specific tank setup, you’ll want to think about adding a few separate pieces of equipment. Bubble counters, check valves, and diffusers will all help you get the maximum benefit from your new regulator.

1. Bubble Counter

   ​Bubble counters, while not necessarily required, help you determine how much CO2 gas is being injected into your tank. As the name suggests, bubble counters measure the number of bubbles being released each second.
   
   

When you use a bubble counter with a CO2 drop checker, you will know precisely when the CO2 levels in your tank have dropped out of your desired range. A high-quality CO2 regulator will have a bubble counter built into it. If this is the case, you do not need an external counter.

2. Check Valve

Check valves are used to help ensure that water is not flowing back into your CO2 system. As CO2 gas is being released, water can find its way back into your regulator. Water getting back into the system can cause it to begin to malfunction. Most high-quality CO2 regulators already have a check valve built into them to ensure this does not happen.

3. Diffuser

CO2 diffusers help your tank utilize the CO2 gas being released more efficiently. An excellent CO2 diffuser will help break up more giant CO2 bubbles into a finer flow so that your water can adequately utilize the gas being released.

The key is matching the size of your diffuser to the size of your tank. The best-sized CO2 diffuser will produce a stream of fine bubbles that are more evenly distributed in your tank. If you do not have a diffuser in your system, the more giant CO2 bubbles will reach the surface of your water more quickly, causing the gas to escape into the air instead of your water.

How To Set Up Your CO2 Regulator

After putting together your system, you’ll want to follow a particular order to begin assembling the pieces of equipment. Following a specific order that starts at your CO2 canister and ends with your diffuser is how you correctly assemble the setup.

From your CO2 cartridge, you’ll lead into your CO2 regulator, and then your bubble counter. Next is your check valve and, finally, your diffuser that releases CO2 into your tank.

1. Attach Your Regulator

   Start by attaching your new regulator to your CO2 canister. Regulators are designed to work with most CO2 cartridges being sold today. This means you usually do not need to worry about purchasing a separate adapter. If you do, chances are high you may need a paintball canister adapter if you are using smaller store-bought CO2 cartridges.
   
   

2. Attach Your Tubing

Once you have attached your regulator to your CO2 source, you will begin connecting the air lines and hoses to your setup. Make sure you are attaching the air line to your outlet. Then, attach the other end of your line to your bubble counter.

3. Attach Your Diffuser

   From your bubble counter, you will attach another piece of air line to your diffuser. Then, you can place the diffuser into your tank where bubbles will be injected into the water. Make sure that the diffuser is attached using suction cups or magnets in an area that receives proper circulation.
   
   

4. Attach Your Drop Checker

   Finally, you can attach your CO2 drop checker inside of the tank in an area where it can accurately measure the concentration of CO2 gas. Pay attention to the drop checker to determine if you need to dial back the amount of CO2 being released or increase the volume.

For most planted aquariums, you will want to maintain a level of 26 parts-per-million to 35 parts-per-million of CO2 gas.

What Happens When CO2 Levels Are Out Of Sync?

Your plants will require supplemented CO2 to photosynthesize nutrients in your tank correctly. Photosynthesis is a process where plants convert CO2 gas and water.

As they absorb light, the light gets converted into sugars and oxygen. This oxygen helps keep your fish alive. The sugars are released and re-absorbed by your plants to help strengthen their leaves, roots, and stems.

All aquariums will have a small amount of gas in the water from your external environment. However, supplementing the gas into your tank will be a requirement as soon as you add plants and fish. For your plants to thrive, and create the oxygen your fish need to survive and thrive, they require supplemented CO2 gases.

If your tank’s CO2 levels drop below a specific amount, plants will stop growing. They will show yellowing on the leaves and stalks and could eventually die. If the plants die, they can release toxins in the water that could harm your fish. It creates a recipe for disaster.

Low CO2 gas levels also give algae a chance to grow out of control. Algae thrive at low CO2 and oxygen levels, especially when you are feeding them a constant source of light. When your water becomes imbalanced, algae begins to grow and stifle the oxygen required by your plants and fish. This also raises your ammonia levels and decreases your oxygen levels.

If you are supplementing too much CO2 gas, though, you could encounter issues with your fish not being able to breathe. You will see them moving to the surface of the water to gasp for air. When this happens, you’ll need to test for CO2 levels to ensure you aren’t choking your fish.

Using a CO2 drop checker, bubble counter, and pH test kit will help you maintain the optimum range in your water.

How Do I Dial-In My Bubble Counter?

Deciding on the specific number of bubbles your tank needs will depend significantly on the size of your tank and the number of fish and plants you have inside of it.

Larger tanks require more CO2 being released to obtain the same optimum level as a smaller tank with fewer fish and plants. Dialling in your perfect amount will require consistent testing and tweaking of your regulator until you’re in the optimum range.

While you are setting up your tank, you can set your regulator to release around one to two bubbles per second. After measuring, if you notice that the CO2 levels are too low, you can begin turning up the volume until you achieve the optimum range.

To give you an example, let’s assume you have a 20-gallon tank that is full of plants. In the initial stages, one bubble per second may be enough. However, if you notice the CO2 levels are not registering or are below your optimum range, you can either trim the plants or increase the CO2.

You want to keep in mind, though, that going too high on your CO2 can reduce the oxygen in the tank and cause other issues. It’s always best to start with a lower amount and gradually increase it than it is to start high and attempt to dial it back.

Is A CO2 Drop Checker Required?

We highly advise using a drop checker to maintain a consistent level of CO2 gas inside of your tank. When your water’s pH level changes (based on the amount of CO2 available), a drop checker will help you quickly determine what needs to be supplemented.

Healthy aquariums should have CO2 levels ranging between 20 parts-per-million and 40 parts-per-million. If your drop checker indicates a blue reading, it means your CO2 levels are low. If the reading is green, it means you have maintained ideal levels. If the color turns to yellow, it means your CO2 levels are climbing and need to be addressed.

Because CO2 drop checkers are relatively cheap investments, it is highly advised that you add one to your system.

What Are The Best CO2 Regulators For Aquariums?

After sorting through dozens of different regulators, we have found the best CO2 regulators for aquariums are the JARDLI CO2 Regulator w/ Built-In Solenoid Valve.