7 Best Aquarium CO2 Regulators of 2021 – Care Your Plants!

Best Aquarium CO2 Regulators Review by Aquarium Tales

Hello aquarium owners, do you want a planted aquarium with thriving, healthy plants? It’s definitely yes, so you are searching for a proper means of accurate co2 dosing.

As an experienced aquarist, you must know how deadly co2 can be for your fish if you don’t add it accurately!

Before arranging co2 adding, we’ll suggest you think and plan very carefully! Because adding co2 is a highly tricky task! For healthy plant growth, you have to maintain a dissolved co2 level between 20 to 30 ppm.

If it goes above 35 ppm, it will start stressing your fish. So, you understand how narrow the margin of safe co2 level is, and the control has to be precise.

Still planted aquariums are very popular, and while maintaining it, at some point, you might need co2 addition for live plants.

If you want bright flourishing plants with co2 dosing, select a quality co2 regulator with high reliability. Only an accurate, reliable co2 regulator can ensure the proper level of co2 in water.

We know it is not easy to pick the best match for you, as so many products are available in the market.

No worry, we have researched to find the best aquarium co2 regulators and enlisted our top picks. Hopefully, this is going to be beneficial for you.

Quick Comparison Of My Top 3 Best CO2 Regulators

Why Should You Use A Regulator?

Healty Fish

Plants and fish develop a symbiotic relationship in the close aquarium system. Fish and other aquatic critters take oxygen and release carbon dioxide through breathing, and plants utilize co2 for photosynthesis to produce their food and oxygen.

Excess co2 in the aquarium develops toxicity and alters the pH balance. If co2 concentration goes past the tolerable range of fish, you may have sick or dead fish. A co2 regulator can prevent that by maintaining a stable co2 level. 

Why do you need a co2 regulator

Thriving Plants

Keeping a planted aquarium thriving, you might need to inject co2. It is crucial to keep the co2 level in an optimum range, and only an accurate co2 regulator can do so.

Sometimes the amount of co2 that comes from the exhalation of fish is not sufficient for plants. If plants suffer from a lack of co2, leaves and stems turn pale; they become unhealthy and weak. 

Living aquatic plants can absorb co2, ammonia, and nitrate and release oxygen; thus, they establish a natural cycle. Only flourishing healthy plants can absorb a sufficient amount of toxic gases to fish, and a balanced level of co2 can make plants burgeoning

Resisting Algae Growth

Algae is unwanted, and co2 level fluctuation is one of the primary reasons for algae growth. Algae often indicate an unhealthy aquarium environment that can cause disease to the fish and affecting plant life.

If the co2 dosing rate is not correct, co2 ppm can swing; therefore, a regulator having steady output can save you from an algae outbreak.

Related Topic: How to set up a complete CO2 system 

Pick The Best Aquarium CO2 Regulator From The List

7 best Aquarium CO2 Regulator

FZONE Pro Series co2 regulator is a dual-stage regulator with so many handy features. A dual-stage regulator is inherently safer to eliminate the ‘end of tank dump,’ which can be catastrophic for fish. Regardless of how much co2 is remaining in the cylinder, this regulator can provide stable output.

Precise control for co2 dosing is crucial, and this regulator has an excellent reputation for it. The pressure adjusting knob is easy to operate, and the output pressure is accurately adjustable from 0 to 65 psi. There are two gauges with the regulator; one shows the bottle pressure, and the other shows output pressure. 

Two manifold blocks are available with the regulator, and both are independently operable with high-precision needle valves. 

A pressure relief valve releases pressure above 100 psi, which is a handy safety feature, and at the same time, it helps easy control. You can adjust the CO2 as low as 20 bubbles per minute, and a bubble counter enables explicit counting.

The bubble counter comes with a check valve that prevents water backflow inside the regulator, as water entrance can damage the regulator.   

The power consumption is as low as 2.5 watts only. The 12 volt DC solenoid is safe, reliable, and runs very quietly. The solenoid functions smoothly and less prone to overheating.  You can incorporate the solenoid with an automatic timer that will make the entire system safer. 


  • Provided with installation fittings and connectors
  • Built-in check valve to protect the regulator
  • Reliable, smooth solenoid valve, designed to work with an automatic timer
  • High-precision of control features
  • co2 proof tubing with the package 


  • Useable with North-American standard cylinder only (not for paintball bottles)

CO2 Art PRO-SE Series aquarium CO2 regulator is one of the bests in the market and offers a five-year warranty! Amazing!! In addition, they have excellent customer service mentioned by the users. 

It is a dual-stage regulator; as you already know, dual-stage is more reliable; therefore, no chance of an end-tank dump. So, it will prevent excess CO2 in your tank, keeping livestock safe. 

CO2 art regulator is well known for its reliability. You can adjust the working pressure up to +/- 40 psi, which is excellent for any aquarium, planted, or marine. 

The product comes along with:

  • 12 V DC integrated solenoid valve
  • Power adapter with universal voltage 100V-240V
  • Bubble counter with a built-in check valve and needle valve
  • Dual gauge pressure indicators
  • 2-black o ring

This CO2 art regulator is compatible with any size CO2 cylinder; recommended is a 5lb aluminum or steel tank. However, you’ll need to buy a paintball adapter to work with paintball tanks. 

I highly recommend this regulator if you want extreme accuracy and safety. However, the price is a bit of a higher-end. 


  • Five years warranty
  • Dual-stage regulator 
  • maintain the constant CO2 level
  • Includes all the accessories required
  • Compatible with any size CO2 tank
  • Threads have been built following the North American Standard.


  • Not easy on the wallet
  • No paintball adapter is included in the package.

This is another FZONE product, and a dual-stage regulator provides stable CO2 pressure and flow rate.  

When pressure is reduced in the CO2 tank, the flow rate doesn’t change, so the CO2 level remains constant at the set pressure. The working pressure is adjustable from 0 to 60 psi. 

Solenoid valve allows you to turn on/off co2 injection automatically using a timer. High precision needle valve with solenoid ensures easy fine-tuning of co2 output; 1 bubble in 03 seconds.

The regulator package includes:

  • Integrated 12 V DC solenoid provides safe and steady operation.
  • Aquarium safe needle valve with solenoid
  • Bubble counter with check valve,
  • Separate CGA320 and paintball adapter. 
  • AC/DC power adapter and power cable
  • Required tools (wrench, sealing ring) to set up
  • Single gauge for output pressure

The Fzone mini-series regulator is made of aluminum alloy. It is compatible with paintball tanks, all CGA320 threaded cylinders, and 5/8” UNF threaded disposable co2 cartridges. However, not suitable for 3/8”.  

This regulator can be installed both horizontally and vertically. It’s a perfect solution for a single tank/unit. 


  • Big pressure gauges are convenient for viewing 
  • Precise controls are the focused feature of this product
  • The solenoid is sound-free and reliable
  • The check valve prevents reverse flow from damaging the regulator
  • Very simple to install and operate


  • Single-stage regulators are less reliable than double-stage ones
  • An extra adapter is required to use with paintball bottles 

The third product of the five best aquarium co2 regulators is the Basic AQUATEK Aquarium CO2 Regulator, in our judgment. What we like the most about this regulator is the material of construction is brass.

Though brass-made products are a little expensive than others, they are highly durable. This product comes with essential features like a bubble counter, a check valve, and two pressure gauges.

The bubble counter makes your measurement easier while adjusting the rate of dosing. The check valve prevents backflow. Two pressure gauges show reading in two units in this regulator, both in psi and kg/cm.

The regulator’s solenoid valve is ‘Cool-Touch’ with an industrial electronic solenoid design and highly reliable. High-quality solenoid with well-designed construction makes this product superior to most other products of the market.

This regulator is compatible with most co2 atomizers and diffusers in the market while also useable with a wide variety of high-density tubing.


  • The material of construction is brass, thus durable and dependable
  • Besides using in freshwater co2 system, it is also useable for calcium reactor
  • The solenoid is of industrial electronic design rated and highly reliable
  • Highly compatible with co2 atomizers, diffusers, and tubing


  • The solenoid does not run with DC power
  • Initial tuning can be a little tricky

If you have enough budget, you can choose this product with unique features that you will not get in most co2 regulators. It is usual, and you have to pay a bit more for better quality.

An easy-to-adjust decompression pressure gauge helps to deliver stable and accurate co2 output. Precise adjustment of co2 is critical to make your plants flourishing and keep fish healthy. 

This regulator can easily adjust the output for a wide range of volume and takes less effort with your finger. You can use this co2 regulator with disposable cartridges.

A patented solenoid magnetic valve is highly reliable, effective, and energy-efficient. The solenoid valve is quiet and does not make any annoying sounds. 

It is specially designed and doesn’t get overheated; thus, it lasts longer. The solenoid is functional with 110 and 220 volts of AC for worldwide use. This electrical equipment is safe to use and awarded CE and PSE certification.

Superior quality parts with improved sealing technology are easy to assemble and less prone to leaking. All necessary safety features are available with this regulator so that you can use it tension-free.


  • Comes with easy to adjust decompression pressure gauge for accurate output
  • Equipped with an energy-efficient patented solenoid magnetic valve
  • The solenoid valve is quiet and cool
  • Useable with disposable cartridge


  • A bit pricy
  • The colorful pressure gauge can create discomfort to read

The DoubleSun aquarium co2 regulator is also constructed with highly durable metal that is less prone to corrosion and rust. The precision of control is awesome, and this regulator can regulate bottle pressure as high as 200 psi.

High compatibility with various co2 atomizers, diffusers, and high-density tubing will make your life easy with this product, no doubt! This product comes with tightening tools, a hex wrench, and an extra seal ring.

The threads for coupling are finely forged so that separate parts are connected smoothly and sealed properly. The professional sealing technology is very reliable, and you don’t have to be worried about leaking.

There is a micro-adjust valve to adjust the co2 output with precision. The accurate fine-tuning is super easy with the valve, and the regulator is capable of keeping the output flow stable.

You can check the number of bubbles with a trim valve, which helps measure co2 dosing easily. A check valve is connected with the bubble counter to prevent the backflow, as water can flow back to the tube by siphoning effect and damage the co2 system.

The solenoid valve is durable and sturdy with high reliability. It comes with an easy-to-assemble feature, making it easy to assemble, dismantle, and adjust. Recently the manufacturer upgraded the solenoid design aiming for better control over output pressure lowering and stability.


  • Good quality product at a reasonable price
  • The dual gauge helps monitoring cylinder pressure and output pressure
  • Improved solenoid design for appropriate output and stability
  • The micro-adjust valve helps accurate fine-tuning 
  • Comes with necessary hand tools


  • The micro-adjust valve is sensitive and requires some fine handwork
  • The solenoid does not run with DC power

This product is the last one on our list of the best aquarium co2 regulators. The ZRDR Aquarium CO2 Regulator is number 2 in our list of the best aquarium co2 regulators. What we like most about this regulator is the high compatibility. 

This regulator is broadly compatible with most brands of high-density tubing to inject co2. You can use this regulator for standard bottles, and with an adapter, it is also useable for paintball bottles.

High precision of control is a focused feature of this product. There is a bubble counter to monitor the co2 output, and you can make bubbles as low as 1 per 3 seconds. Accurate control over co2 dosing can make your plants flourishing and keep your fish healthy.

The bubble counter is assembled with a check valve, and the check valve prevents the reverse flow of water to the co2 system. If water enters the regulator, it can be damaged.

The regulator comes with two big dual gauge displays. The broad view of the gauges is easy to read. One of the meters shows the co2 bottle pressure, and the second one shows the output pressure. Comparing the two pressure values, you will get an indication of how properly the regulator is working.

The solenoid of the regulator is a 12 V DC regulator that is safe to use and dependable. The solenoid does not make any annoying noise and does not get overheated. A reliable solenoid is vital as it is one of the safety features to ensure proper dosing of co2.

This product is made of aluminum alloy, thus less prone to be rusty and corroded. You will get the manufacturer’s instructions with the box. This is simple to install, and if you are a first-timer with co2 dosing, you will find this product convenient.


  • Big pressure gauges are convenient for viewing 
  • Precise controls are the focused feature of this product
  • The solenoid is sound-free and reliable
  • The check valve prevents reverse flow from damaging the regulator
  • Very simple to install and operate


  • Single-stage regulators are less reliable than double-stage ones
  • An extra adapter is required to use with paintball bottles 

Working Principle of Aquarium CO2 Regulator

best aquarium co2 regulators review

How does a CO2 regulator work? It is not so difficult; a co2 regulator adjusts co2 output pressure to ensure the controlled delivery of co2. According to the preset adjustment, a regulator transfigures the high pressure of a co2 cylinder to lower feasible discharge pressure.

You can control the quantity of co2 dosing by adjusting the output pressure. How ease of controlling a regulator can provide for users is the most crucial consideration. A co2 regulator has to be precisely accurate and easy to maintain.

There is a pressure adjusting knob by which the user sets the desired pressure. Rotating the knob clockwise, you can increase the pressure and vice versa.

Ideally, a regulator has two pressure gauges from those you can see the cylinder pressure and the regulated pressure. The higher output pressure indicates the more co2 you are adding.

Now the question is how you will set the co2 output! You have to count the bubble produced by co2. If your regulator has not come with a bubble counter, you can count bubbles visible in the aquarium water.

Still, we suggest having a bubble counter for precise control. There is a thumb rule, one bubble per minute for every 2.5 gallons. Sounds not that tough, right?

How to Choose the Best Aquarium CO2 Regulator

As the co2 regulator is an essential component of the co2 injection system, you will have to be very selective about it.

Before buying, you will have to focus on some features, and we discussed some below, believing those criteria can make one the best aquarium co2 regulators. 


Dual-stage regulators step down the pressure in two stages. CO2 from the first stage with low output pressure enters the second stage for further lowering. Double-stage regulators are safer in terms of reliability.

There is less chance of malfunction and pressure fluctuation, and they are easier to control precisely. However, double-stage regulators are more expensive than single-stage regulators. 

When the bottle pressure comes to low at the end, there is a chance for single-stage regulators to let vast amounts of co2 pass, and this term is called ‘end of tank dump.’  Double stage regulators eliminate the risk of this sudden dumping. 

Materials of construction

It would help if you chose a regulator that is less prone to corrode. The material of construction plays the most vital role in preventing corrosion. If a regulator is internally corroded, it will malfunction, and the pressure adjustment will not be precise.

Once you bought a long-lasting product, though a little expensive, it will save you money in the long run. Try to buy a regulator made of brass or stainless steel. 

Ease of use

Every co2 regulator requires manual adjustment; make sure that your finger work does not become too hard.

Usually, a rotating knob is used to adjust the regulated pressure; this knob should be smooth and easy to rotate.

You have to check the pressure gauge reading is clear enough and easy to read. 


If you are buying a regulator for multiple tanks, you will need a regulator that can handle a higher flow rate. A small one, compatible with typical paintball cylinders (24oz), is sufficient for single tanks.

There are fixed output regulators in the market, and if you buy such one, make sure the capacity can meet your need.  

Essential Accessories of A CO2 Regulator

Bubble Counter

The bubble counter is an essential accessory, as it indicates the rate of co2 entering your aquarium. It will make your measurement of co2 injection easier.

The bubble count per minute will tell whether you should regulate the discharge pressure to a higher or lower value. Ideally, in a 20-gallon aquarium, one should dose 8 bubbles of co2 per minute.   

Solenoid Valve

Plants can utilize co2 through the photosynthesis process, and this process needs light. So in the absence of light, there is no use of co2, and it will become excess if you keep dosing continue.

You must never overdose co2 in the water for your fish’s safety. A solenoid valve enables an auto-on/off feature with a preset timer. Saving excess usage of co2 is also economically beneficial. 

Pressure Gauge

Most of the co2 regulators come with two pressure gauges. One of those shows the bottle pressure, and the other one shows the output pressure. The second one is more important as it is the releasing pressure of co2 to the aquarium.

Both these pressure readings are important, the first one will show the remaining stored amount in the bottle and the second one is a measure of dosing rate. 

Pressure Relief Valve

The pressure relief valve is a safety feature, it relieves any excess pressure. Unwanted high pressure can result from malfunction of the regulator or if the downstream tubing is somewhere blocked.

An unwanted high pressure can cause a sudden release of excess amount of co2 in the water, and that can be devastating for fish. A pressure relief valve thus ensures precise control. 

Check Valve

A check valve is a non-return valve that prevents reverse flow. This one is another safety feature to avert something flowing to the co2 system. It is not unusual that without a check valve, water can get into the co2 system and cause damage to it.  

When You Shouldn’t Inject CO2

If your plants are flourishing with bright green colors, it indicates they are getting proper nutrition and they are not suffering from co2 deficiency. When your plants seem happy, you should not be worried about taking proactive measures to add co2.

Plants can utilize co2 through the photosynthesis process, and light is essential for this process. Only high light plants absorb a significant amount of co2, while low light plants cannot take that much.

On the other hand, if you do not arrange enough lighting in the aquarium, plants cannot absorb co2, regardless of their type.

Extra co2 can be deadly for your fish. One thing you should remember co2 is only suitable for your plants, not for your fish. Excess co2 rich environment; levels above 50 ppm can be suffocating for them.

How Do You Know the Right Amount of CO2 in Your Aquarium?

Measuring CO2 level with Drop checker

The amount of co2 requirement varies from tank to tank because every setup is unique. It depends on a few factor: 

  • Amount of fish stocking
  • Your tank size
  • Types and how dense is your planted aquarium
  • Lighting duration and intensity
  • The extent of water movement

Whatever are the factors, you can easily find the correct level of co2 in your aquarium. 

There could be many different ways; however, the best, cheapest, and easiest way is to use a drop checker. It won’t come along with the regulator package; you need to purchase independently. 

The drop checker is a simple glass-made device attached to your aquarium with the help of a suction cup.  It’s filled with a fluid of 4 dKH with a pH reagent. When co2 from the aquarium water goes into the drop checker, it causes a reaction and the color of the solution changes. 

The green color indicates the perfect co2 level, while yellow means too much, and blue symbolizes not enough co2 level. 

Installation and Operation

The installation of a co2 regulator is not a challenging task. The most common types of co2 bottles available in the market are standard types and paintball types.

The setup procedure may slightly differ for various co2 systems, but the basic steps are the same. You will need hand tools like an adjustable wrench and spanner for this task.

If you find it easier for you to understand clearly with a video demonstration, you can watch the video below. Also, you can read the subsequent section on how to install a regulator. Follow the step-by-step guideline. 

Step-1: Attach the Regulator (Use Basic PPE)

First, ensure the bottle side valve is fully closed because you are working on a pressurized system. A momentary carelessness can cause serious injury. We recommend wearing basic PPE like cotton gloves and safety goggles during installation.

You will get a gasket with the regulator box and place it inside the regulator nut that attaches the regulator with the bottle. Then you have to screw the regulator with the bottle.

Tighten the nut gently with your hand. After hand-tightening the nut, use an adjustable wrench or properly sized spanner for further tightening. Just secure the regulator and don’t overtighten.

Step-2: Connect the Tubing 

The next step is to insert the co2 tubing and tighten it firmly with the nut (but only hand tightening). You have to ensure no leakage through the pipe joint; otherwise, co2 loss will waste your money.

Nowadays, manufacturers are making co2 regulators with easy-to-fit connectors, and those are useable for a wide range of co2 systems. So the necessary fittings and connectors are less concerned these days.

Step-3: Power Up the Solenoid Valve

Once you have attached the regulator with the bottle and connected the co2 tubing, power up the solenoid valve; there are indicator lights to confirm the solenoid is powered up in some solenoids. The solenoid valve should be open when it gets power.

Step-4: Open Bottle Isolation Valve

Now your installation is done, you are ready to inject co2 into your aquarium. At first, place the co2 tube somewhere suitable inside the aquarium. Open the bottle side isolation valve, and you can see the bottle pressure from one of the pressure gauges.

Step-5: Adjust the Output Pressure

Slowly open the pressure adjusting knob and monitor the output pressure from the second pressure gauge. Initially, set the out pressure at 30 to 50 psi.

After once the pressure is stabilized, you have to do some fine-tuning to achieve the desired bubble count. Typically for every 2.5 gallons of water, one bubble per minute should be ideal.

Step-6: Check the Bubble Counter 

If your co2 system does not include, we’ll suggest having a bubble counter. A check valve and a diffuser can make a perfect combination with the bubble counter. The diffuser forms bubbles of co2 that can nicely be permeated in the aquarium.

You can use a drop checker to place it in the fish tank with a suction container to check the co2 concentration in the water. This is another helpful tool to maintain the proper co2 level in the water, which is extremely important.

Final Words

I don’t think co2 dosing will bring a lot of hassles for you. There are many benefits of a planted aquarium over an only-fish aquarium. Though you are giving extra effort to take care of live plants, they will minimize your labor in many ways.

In a properly maintained planted aquarium, fish can thrive because live plants can establish a natural filtration cycle that keeps the aquarium environment clean. Because of that, planted aquariums usually require less cleaning than other aquariums.

Have you found our article helpful in choosing the best aquarium co2 regulator? Choosing the right tool is the best way to get relief from stress and anxiety. The co2 regulator is such an item you can never compromise its quality.

We suggest keeping a moderate budget to buy a quality product, otherwise don’t go for co2 addition and think of an alternative. If you have any thoughts or suggestions, please drop us a comment below!

3 thoughts on “7 Best Aquarium CO2 Regulators of 2021 – Care Your Plants!”

  1. Hi Sujit!
    Thanks for sharing a great article.
    I’ve bought Fzone CO2 regulator based on your review and I’m very happy with that purchase. It works great. Nice design, easy adjustments made. Came with everything I needed for my aquarium. Also came with an adapter to use on a paintball tank. I really like how the co2 hose connects to the regulator.

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