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Supplying your aquatic plants with additional CO2 can be the difference between a mediocre planted tank with a few slow-growing plants and an abundant aquascape buzzing with vibrant color.

CO2 systems are not without their risks, though. These kits are highly pressurized and can cause serious harm or even death to your fish if something goes wrong.

It’s essential, then, to find the best regulator to be a joy to use and give you peace of mind.

Let’s take a look at the best CO2 regulators on the market. Starting with the best budget, single-stage models, then moving on to the best premium grade dual-stage setups.

The Best Budget Single-Stage CO2 Regulators

INKBIRDPLUS Aquarium CO2 Regulator DC Solenoid With Dual Gauges and Bubble Counter

This kit features a robust aluminum alloy construction, easy-to-read pressure gauges, and a quiet DC Solenoid.

What stands out on this regulator is a trimmer valve specifically designed for aquariums. It’s easy to fine-tune and get the CO2 flow just as you want, lacking in some of its competitors. It also has a fairly good leak-proof design for a budget regulator.

The package also contains two components that some other kits don’t: A useful bubble counter and an essential check valve.

On the flip side, this is only a single-stage regulator, so there’s always that danger of a sudden CO2 dump in your tank when the CO2 tank is nearly empty. It’s also only compatible with larger CO2 canisters.

Things We Like:

• Excellent trimmer valve for fine-tuning a constant flow.
• Solid design.
• A generous package for the price with extra components.

Things We Don’t Like:

• Only single-stage regulation means there’s a danger of CO2 dumping.
• Not compatible with smaller, paintball-sized CO2 canisters.

FZONE Aquarium Co2 Regulator DC Solenoid, BubbleCounter, and Check Valve

This is another impressive kit for a budget price. It has most of the features you wish for in a CO2 regulator and won’t break the bank!

This model has dual gauges, one for the pressure in your CO2 tank and another for the CO2 pressure going into your aquarium. It has fairly accurate flow control that allows for good regulation, and the DC Solenoid is a real plus as it makes this regulator very quiet.

The bubble counter is a nice addition, giving you a more precise reading of the CO2 input. The check valve is also very welcome, so you don’t have to go and buy one separately.

The kit includes all the tools you need for setup, although the instructions could be clearer. The unit is made from aluminum and includes a one-year manufacturer’s warranty. The customer service at FZONE is extremely helpful!

Things We Like

• Impressive selection of tools – a complete regulator kit!
• Great value for money
• Good customer service

Things We Don’t Like:

• Aluminium build is not as strong as stainless steel, brass, or copper equivalents.
• Instructions need improving for beginners to set up easily.

VIVOSUN Argon/CO2/Helium Regulator Emitter System

The VIVOSUN Hydroponics CO2 Regulator is one of the least expensive regulators on the market. The manufacturers have managed to help make CO2 regulation available to everyone by offering this regulator at an unbeatable price.

It features an industrial solenoid valve, 5 meters of free plastic dispensing tubing, and a hose tail to suit a 4.2 mm hose diameter.

The Adjustable valve is rather over-sensitive and difficult to set precisely, especially for smaller tanks.

The brass build and industrial-grade solenoid should theoretically help this regulator last several years. However, some customers have reported leaks and occasional glitches with the gauges. Not surprising for a super-budget option!

Things We Like

• Very low price for those on a budget.
• Attractive brass design.

Things We Don’t Like:

• Too many potential glitches
• Adjustable valve is difficult to set perfectly, especially for small aquariums.
• Unreliable CO2 regulation can kill fish, so be careful if you’re looking for a bargain!

The Best Premium Grade Dual-Stage CO2 Regulators

CO2 Art PRO-SE Series Aquarium CO2 Dual Stage Regulator

This is the latest addition from the German brand CO2 Art, which has a great reputation for top-quality CO2 regulators. This brand-new dual-stage design is ideal for those looking to get a super accurate and safe CO2 flow.

Adjustable working pressure of +/- 40PSI (3 BAR) makes this a great choice for freshwater and marine aquariums and is suitable for up to 1000 gallons of nano tanks!

On top of this, the CO2 Art PRO-SE Regulator comes with a 5-year warranty, which really helps to build trust, knowing you’re buying a reliable piece of kit from a reputable manufacturer.

One of the few drawbacks would be that this regulator can only be used in a single tank, but it’s our top pick on the market for the price if you just need one.

Things We Like

• Amazingly precise control on the bubble count.
• Strong, reliable build from a brand you can trust.
• 5-year warranty to give you peace of mind.

Things We Don’t Like:

• Only suitable for a single tank at a time.

MagTool Aquarium Dual Stage Co2 Regulator DC Solenoid and Expendable Manifold

A very solid, dual-stage regulator for serious hobbyists and professionals. The dual-stage regulator means that you’re fully insured against fatal dumps of CO2 that could otherwise poison your fish. A worthwhile investment for your peace of mind!

It’s made from an attractive copper construction and is quite a solid build. The double gauges are large, clear, and easy to read.

Another great feature of this regulator is the Modular Block Design. Two manifold blocks, each with its own high-precision needle, allow you to operate CO2 flow in two aquariums simultaneously and independently.

While it might be twice the price of a cheaper model that can only send CO2 to one tank, getting one high-quality regulator like this makes a lot of sense if you have two tanks.

The customer service offered by Magtool is also very good, should you have any issues.

Things We Like

• Strong, copper construction.
• Dual stage regulator for peace of mind.
• Can be used in two tanks simultaneously.

Things We Don’t Like:

• Occasional reports of leaky gauges.

SR Aquaristik Dual Stage Co2 Regulator Kit Bubble Counter and Solenoid Valve

Another top-quality dual-stage CO2 regulator. The high-precision needles live up to their name and make it easy for you to set an accurate bubble count/ flow rate.

The gauges are easy to read, and the bubble counter has a built-in check valve.

An additional built-in safety valve releases pressure automatically when it exceeds the limit.

Very safe, reliable, and solid build.

Things We Like

• A solid piece of kit, well-built.
• Excellent dual-stage and safety valves offer peace of mind.
• Precise needles that are easy to set.

Things We Don’t Like:

• High price!
• Only designed to be used on one tank at a time.

Everything You Need To Know About CO2 Regulators

Most aquarium owners will be familiar with the fundamental equipment of fish-keeping – a tank, a filter, a heater, and lighting.

Extra bits of kit like CO2 injection systems might seem a little hi-tech and daunting to novice aquarists. What exactly is a CO2 regulator, and is CO2 injection really necessary anyway?

Well, those are great questions to get us started in learning all about CO2 regulators!

What Is a CO2 Injection for Aquariums?

CO2 injection is a pressurized system that injects additional CO2 into aquariums to boost plant growth.

Every plant needs CO2 to photosynthesize, and a small amount of CO2 will already be dissolved in your water for your aquarium plants to absorb and grow.

In heavily planted tanks and aquascapes, however, the normal levels of CO2 in the aquarium might not be enough to see the plants truly thrive. This is why some aquarists like to add extra CO2 to the water via carbon dioxide injection systems.

Is CO2 Injection Really Necessary?

Many aquarium owners grow a few plants in their tanks without any additional CO2. Some people will simply prefer the setup of a low-tech system with the minimum pieces of equipment possible.

However, if you’re serious about aquarium plants, CO2 injection really takes things to the next level. There’s a world of difference between plants with plentiful nutrients and CO2 and those given the bare minimum to survive.

If you want a planted tank or aquascape that glows with vibrancy, then CO2 injection is a must.

Check out this video to learn from a hobbyist who tried CO2 injection for the first time and quickly became impressed with the difference it made…

What Is a CO2 Regulator?

A CO2 regulator is an essential part of the CO2 injection system. Essentially it’s a simple device that sits between the pressurized CO2 tank and your aquarium to regulate the right amount of flow to your fish tank.

This is an incredibly important job because while CO2 nourishes your plants, excessive levels of CO2 will kill your fish and any other animal life in your tank! Finding a safe, reliable regulator, therefore, is essential.

Single-Stage vs. Dual-Stage Regulators

Our review above divides CO2 regulators into single- and dual-stage models. This is the number one difference between a budget regulator to a high-quality, reliable one.

CO2 tanks are highly-pressurized, making it difficult for a single regulator to moderate the flow levels accurately and consistently.

A dual-stage regulator is essentially two regulators in one. The first stage reduces the pressure to a slower flow that the second stage can assign far more precisely.

This is a big consideration and may well be worth the extra investment for the peace of mind it’ll give you that your fish will definitely remain safe!

The Components of a CO2 Regulator

Pressure Gauges

Your CO2 regulator will come with at least one gauge to measure the amount of CO2 in your cylinder. Most regulators now also come with a second gauge that tells you how much CO2 pressure or flow goes into your aquarium.

The main thing to look for in a good gauge is that it’s large and easy to read. A surprising number of pressure gauges on the market are rather small and difficult to make accurate readings from. Pressure gauges also need to be strongly built to prevent leaks.

Leaks are one of the biggest issues concerning cheaper CO2 regulators, so buying from a brand you can trust is just as well.

Precision Needle Valves

Needle or pressure relief valves, as they’re sometimes known, allow you to control the flow of CO2 going into your aquarium. If they’re well made, they can also help prevent CO2 dumps – high levels of CO2 being dumped into your aquarium when the CO2 canister is nearly empty, and pressure is low.

Needle valves allow you to adjust the number of bubbles per second, which a bubble counter can monitor.

Bubble Counters

A bubble counter is an optional extra component that some regulator kits will include as standard. They allow you to read exactly how much CO2 goes into your aquarium by measuring the number of bubbles in the bubble counter’s chamber.

While not essential, bubble counters are a really useful extra accessory since they allow you to measure CO2 flow with precision. Very handy when dealing with a gas that could be fatal to your fish in large enough quantities!

Solenoid Valve

An electric solenoid valve allows your CO2 flow to be turned on and off via a timer switch.

This is important because your plants only need CO2 during daylight hours.

With a solenoid switch, you can set the CO2 flow to turn off at night and on again a couple of hours before morning so that your aquatic plants have enough CO2 when they’re photosynthesizing without wasting any extra.

AC vs. DC Solenoids

AC solenoid switches are less complex than DC solenoids but also make a lot more noise and tend to get overheated if they’re on for a long time. Luckily, most solenoids on CO2 regulators are DC, which run much quieter and cooler and save electricity.

Check Valve

The check valve is a valve that stops water from the aquarium from going back up the CO2 feed tube and into the regulator. Since water in the regulator can render it useless, a check valve is essential. Most kits have a check valve, but it’s worth checking! If not, you’ll have to purchase one separately.

Tubing

The right tubing is sometimes included in a CO2 regulator kit, but not always. If you need to buy your tubing separately, ensure it is designed to handle CO2! Some types of tubes will not cope with the cold temperatures and pressure inherent in CO2 systems.

Drop Checker

A drop checker allows you to monitor levels of CO2 present in your water via a color indicator inside a drop-shaped tube in your aquarium. This is an essential piece of kit for safe CO2 injection but doesn’t often come with a CO2 regulator – you’ll normally need to purchase it separately.

Blue means there is no CO2 present, dark green means you’re just at the right level, and yellow means too much CO2 in your water, which could endanger your fish.

The NilocG Aquatics CO2 Drop Checker is a good example of a solid and reliable drop checker.

FAQs

What Are the Dangers of CO2 Injection?

As we’ve mentioned, too much CO2 in your tank is dangerous to your fish, even proving fatal if the tank receives a sudden CO2 dump when you’re not watching.

It’s another good reason to switch the CO2 flow off at night. Your plants don’t need any CO2 during the night, and it’s also the time you’re least likely to notice any problems.

Can CO2 From Aquariums Be Harmful to My Health?

CO2 injection is quite safe for your health when used responsibly. CO2 occurs naturally in the air around us, and a little extra shouldn’t harm you unless your carbon dioxide regulator were to spring a bad leak in a confined space.

However, you need to be careful when changing the cylinder or dealing with leaky valves since the CO2 in the cylinder is extremely cold, which could damage your skin. Always wear gloves and take sensible precautions when changing your cylinder or adjusting any components of your CO2 system!

How Do I Know if I Have a Leak in My CO2 System?

Unfortunately, cheap regulators often spring leaks.

If you suspect you have a CO2 leak, try the soapy water test! Rub or spray soap bubbles around your regulator and connection hoses to see if any carbon dioxide gas leaks from any components or connections. If there’s a leak, the bubbles will fizz and grow larger, allowing you to identify the exact location of the leak.

You can temporarily fix a small leak by tightening connections or sealing them with Teflon tape, but leaky components need to be replaced in the long run.

How Do I Know if CO2 Levels in My Aquarium Are Getting Too High?

As mentioned, you’ll need a drop-checker. Keep an eye on it to make sure it remains green. Yellow indicates CO2 levels that are dangerous to your fish.

In addition, fish living in a high CO2 environment may appear ‘drunk,’ drowsy, and uninterested in food. If high levels of CO2 are sustained, fish may become stunted, and their reproductive systems can become inhibited.

As a rough guide, 1 bubble per 3 seconds per 5 gallons of water should be the optimum level of CO2 during the daytime in an established planted aquarium.

Does CO2 Injection Reduce Algae Growth?

Extra CO2 can potentially reduce algae growth by boosting the growth of your aquarium plants which will, in turn, absorb more of the nitrates and phosphates in the tank’s water that algae thrive on. Increased plant growth can also reduce the amount of light penetrating the lower reaches of your aquarium, where much of the algae may be growing.

In summary, CO2 means abundant plant growth. Increased plant growth means less light and lower nutrient levels, which in turn means fewer algae.

What Other Kit Will I Need To Get Started With CO2 Injection?

The main three elements for CO2 injection systems are a CO2 tank, regulator, and diffuser.

CO2 tanks come in different sizes, but most regulators are set up to attach to large CGA320 CO2 cylinders. You may need an adaptor to fix them to smaller tanks such as CO2 paintball or soda stream canisters.

A diffuser is the part of the kit placed in the water to break down large CO2 bubbles into tiny bubbles released into the water.

Diffusers need to be purchased separately from CO2 regulators. Like with any other part of a CO2 system, it’s a good idea to get a good one! The JARDLI Music Glass CO2 Diffuser for Aquarium Planted Tank is not only reliable but beautifully made, which can make CO2 injection visually pleasing too.

Our Top Picks

Our top pick for the best single-stage CO2 regulator is the INKBIRDPLUS Aquarium CO2 Regulator. Its tidy design and accurate trimmer valve for fine adjustment give it the edge over its competitors. It also includes a bubble counter and check valve, which is everything you need for a functional regulator.

Single-stage regulators bear the risk of sudden CO2 dumps, so those who can afford it should consider investing in a robust dual-stage regulator.

Our top pick for the best dual-stage CO2 regulator goes to the CO2 Art PRO-SE Series Aquarium CO2 Dual Stage Regulator.

This is an exceptional kit and still within the budget of any serious aquarist. We love how this regulator is super reliable, safe, and accurate and is suitable for a large range of tank sizes.

It’s also made by a trusted brand that offers the best warranty we’ve found among other regulators at a similar price. CO2 Art is clearly confident that this innovative piece of kit will last at least 5 years, so the buyer can be too.

Click here to get your hands on the excellent value INKBIRDPLUS Single-Stage Aquarium CO2 Regulator.

For a top-of-the-range dual-stage CO2 Art PRO-SE Series Aquarium CO2 Regulator. with a 5-year warranty – click here.

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