My Guide For Buying The Best Aquarium CO2 Regulator

If you want a thriving planted tank, you need to make sure they’re getting the correct levels of CO2. Not enough, and they’ll die. Too much, and you risk killing your fish and promoting algae growth.

 

That’s why buying a quality CO2 regulator is one of the best ways you can ensure you provide the optimum levels of CO2, without risking your aquarium.

 

However, not all regulators are made equal.

 

Luckily for you, I’ve done quite a lot of research into find the best CO2 regulators at affordable prices. In this buyer’s guide, I’m going to share with you my tips on choosing the best CO2 regulators, then at the end, I’ll review some of them for you.

 

Let’s get started.

 

Safety Message:

 

This isn’t to scare you, it’s just to make you aware.

 

1. CO2 is not toxic, however it is odorless, colorless, tasteless, and can displace oxygen. If you keep your setup in a small space, a leak could result in a bad atmosphere. You may not realize until you keeled over.

 

This generally applies to DIY setups, but it’s good to know. And you should always ensure there are no leaks by using soapy water.

 

2. As CO2 comes out of a compressed cylinder, it transforms from a liquid to a gas. The gas is -110F, which can cause instant tissue damage. It also generates a strong static discharge. If you opened the valve on an unregulated cylinder, you might get a shock.

Safety lesson over, lets get into it.

 

Quick Comparison For The Best CO2 Regulators

Preiview
S.T. International Aquarium 2-Gauge Professional CO2 Regulator, Silver
AQUATEK CO2 Regulator Mini
U.P. Aqua Co2 Regulator for Aquarium
Top Pick
SR Aquaristik Aquarium Dual Stage CO2 Regulator
Title
S.T. International Aquarium 2-Gauge CO2 Regulator
AQUATEK CO2 Regulator Mini
Up Aqua CO2 Regulator
SR Aquaristik Aquarium Dual Stage CO2 Regulator
Single Stage
Dual Stage
Solenoid Valve
Check Valve
Bubble Counter
Price
$143.17
$160.00
$94.98
$157.98
Prime
-
-
Preiview
S.T. International Aquarium 2-Gauge Professional CO2 Regulator, Silver
Title
S.T. International Aquarium 2-Gauge CO2 Regulator
Single Stage
Dual Stage
Solenoid Valve
Check Valve
Bubble Counter
Price
$143.17
Prime
Details
Preiview
AQUATEK CO2 Regulator Mini
Title
AQUATEK CO2 Regulator Mini
Single Stage
Dual Stage
Solenoid Valve
Check Valve
Bubble Counter
Price
$160.00
Prime
-
Details
Preiview
U.P. Aqua Co2 Regulator for Aquarium
Title
Up Aqua CO2 Regulator
Single Stage
Dual Stage
Solenoid Valve
Check Valve
Bubble Counter
Price
$94.98
Prime
Details
Top Pick
Preiview
SR Aquaristik Aquarium Dual Stage CO2 Regulator
Title
SR Aquaristik Aquarium Dual Stage CO2 Regulator
Single Stage
Dual Stage
Solenoid Valve
Check Valve
Bubble Counter
Price
$157.98
Prime
-
Details

**Before reviewing the individual regulators, I’d like to talk about how you can effectively choose one for your current setup.


Otherwise, if you’re just here to get a detailed breakdown of your options, you can jump straight to the review section.

 

Why You Need a CO2 Regulator

If you want to keep healthy aquarium plants, the likelihood is you’re going to need CO2 injection, because it plays a vital role in the way plants photosynthesize.

 

I’m not going to go into a huge amount of detail on photosynthesis because I think you probably already know how it works.

 

Here’s what you do need to know:

 

In the wild, plants will get their CO2 in large quantities from natural substate (mud etc.), and degrading plants. However, in your enclosed aquarium, CO2 is limited, tap water is depleted from CO2, and plant decay is minimal.

 

So you need to supplement this lack of CO2 with an injector. But, you need to regulate it.


Besides from wasting your money (you’ll inject more than you’ll need), too much CO2 can lead to excess algae growth, because your plants won’t be able to use the CO2 fast enough to out-compete the algae.

 

Or you could kill your fish, because the high levels of CO2 will displace the oxygen and suffocate your fish.

 

Now, every aquarium setup is different. The amount of CO2 you need will depend on a few factors:

  • Volume of your tank
  • Type and amount of plants you own
  • How much light you give your plants
  • The amount of fish in your tank
  • Amount of water movement

To determine the amount of CO2 your tank needs can take a bit of tweaking. The best and fastest way to do this is to use a drop checker.

 

A drop checker is a simple device made of glass or plastic. It sits in your tank an with a solution inside, CO2 will leak from your water into the drop checker and cause a reaction, causing the solution to change color:

  • Blue = not enough CO2
  • Green = CO2 levels are spot on
  • Yellow = too much CO2

Why You Don’t Need a CO2 Regulator

Medium to high-lit plants tend to require CO2 because with higher levels of light, the fast plants tend to grow, the more CO2 they require.

 

However, if you’re keeping low-lit plants, they’re less stimulated to grow. Extra inject CO2 is not always required as there is normally enough CO2 coming from surface agitation, fish respiration, and organic breakdown of dead plant matter.

 

This doesn’t mean you can’t use CO2 injection. Adding it can still improve the quality of growth and health of your plants, you’re just going to need less of it.

 

How to Choose the Best CO2 Regulator

I’m now going to share with you what I believe the be the main factors you should consider when looking to buy a CO2 regulator, and what I will base my reviews off of.

 

This includes:

  • Ease of use
  • Readability
  • Is it dual stage?
  • What CO2 cylinders is it compatible with?
  • What’s it made of?
  • What kit does it come with? (most important)

Let’s break these down, one-by-one.

 

Ease of Use

For the most part, installing your CO2 regulator is very easy. It tends to be as simple as connecting a few tubes and turning a few knobs.

 

However, you want to have to spend hours twisting and adjusting the knobs to get the right amount of CO2. It’s good to know, even the very best CO2 regulators will require some fine finger work. But, you don’t want this to be excessive.

 

Readability

Now, what I mean here is, how easy is it to read the gauges. If, you’re like me and your eyesight isn’t as great as it used to be, you’ll appreciate an easy-to-read gauge.

 

Is it Dual Stage?

If you’re new to the hobby, it’s good to know about these. Dual stage regulators are two regulators built into one. The first stage knocks the pressure down to a regulated (constant) PSI for the second stage.

 

This prevents fluctuations due to changing PSI from the from the tank. Two-stages will add extra protection.

 

It’s true, a single-stage regulators are less expensive and are commonly used with no issues. However, it adds risk and can be more difficult to get a reliable and consistent output.

 

What CO2 Cylinders is it Compatible With?

This will depend on your situation. If you’re going to using your regulator for multiple tanks, you’re going to need one that is compatible with the large 5lb CO2 cylinders. Or you'll be replacing your CO2 regularly. 

 

On the flip side, if you find it hard to get your hands on 5lb CO2 cylinders or you only want it for one tank (depending on the size). You may want to look into getting one that is compatible with regular 24oz paintball cylinders. These, by the way, are very easy to get your hands on.

 

What’s it Made of?

Higher-quality materials means it’s going to last longer. And no one likes to invest in something that will break easily. Stainless steel and brass are your best options.

 

What Kit Does it Come With?

Some of these are more a bonus, and some are must-haves. I’ll let you know which ones as we talk about each.

 

Needle Valve

If you want a safe, quality regulator–a needle valve (sometimes called a pressure relief valve) is a must. It gives you precise control over the amount of CO2 entering your aquarium.

 

Needle valves allow you to finely tune and regulate the rate of flow (CO2 bubbles per second), at your desired level.

 

It’s important you invest in a high-quality needle valve because it help you avoid the scary “end of tank dumps”. As the liquid CO2 in your cylinder get low, the pressure decreases, which can lead it to an increase in output pressure and potentially dump anything left into your aquarium.


A quality need value will control this. Functioning as gateway, controlling the volume of CO2 entering your aquarium, stabilizing the increase in output pressure and stopping the “dump”.

 

Bubble Counter

This is a visual tool, making it easy for you to measure the number of bubbles per second entering your aquarium.

 

A bubble counter isn’t a deal-breaker, as many don’t include one. But, I do recommend you get one as it allows you to make fine adjustments to flow rate.

 

Solenoid Valve

A must have in my opinion.

 

Solenoid valves save you money by stopping you wasting CO2 during the “lights-off” hours when your plants no longer need CO2, because they allow you to put it on an automatic timer.

 

It’s even better if it comes with a light to tell you if it’s on or off.

 

Now, you can simply turn off the CO2 supply manually on a CO2 regulator without one. However, in most homes there isn’t always someone around at the right time to do this.

 

This is one of my favorite pieces of kit which comes with regulators.

 

Pro Tip: Set it to turn off 1 hour before the lights go out. There will be enough CO2 in our aquarium to last the hour. Then start it 1-3 hours (depending on the size of your tank), before your lights come back on. It ensures your CO2 levels are at optimum levels for when the photo period starts.

Gauges

It will have two gauges: one for high pressure and one for low pressure. The high pressure gauge must read at least 1000 psi as most CO2 tanks have 800 psi.

 

Low pressure gauge should read at least 15-30 psi and a maximum of 200 psi. 30 psi gauges tend to mean the regulator outputs a max of 15 psi.

 

Any lower, and it will output 10 or lower psi, this is unsuitable for aquariums. Low pressure gauges over 200 psi means it will be difficult to adjust the pressure the to ideal range between 15-30 psi.

 

Dual-gauge does not mean dual-stage.

 

Check-Valve

If it’s not included in the kit, you’ll need to buy one.

 

This is an important safety feature, preventing a back-flow of tank water into your CO2 regulator. When your CO2 dissolves in water, it re-enters the tubing once the injection of CO2 has stopped.

 

If you don’t have a check-valve, the water could reach your regulator and break it.

 

Tubing

Don’t worry if a kit includes this, but it is a bonus as you can never have too much. It’s inexpensive, and you can easily purchase this separately.

 

Just make sure it’s CO2 resistant tubing. Regular airline tubing does not have the correct properties to be used safely.

 

The Washers

This might seem small. However, if the washers are an unusual size, it can be a real pain trying to find replacements. If I don’t mentions the washers in the review, it means they are standard and easy to find.

 

Reviews For The Best CO2 Regulators

Now you know what to look for when buying a CO2 regulator, you’ll be able to use the comparisons below to make a more informed decision about which one is right for you.

 

S.T. International Aquarium 2-Gauge CO2 Regulator

Features:

  • Dual gauge
  • Pressure relief needle valve
  • Solenoid valve
  • Flow adjustment needle valve

 

The S.T. International 2-gauge CO2 regulator is durable and reliable, so you’re unlikely to experience leaks. The flow adjustment valve makes it easy to adjust the bubbles, although it may take some patience to get it perfect.

 

Its patented solenoid magnetic valve is energy efficient and operates quietly, which is always a nice bonus. And it’s been awarded CE and PSE certification and international patent approved to ensure safety.

 

You can use this with large US cylinders or smaller disposable ones.

 

The gauges use the colors of the rainbow, which personally I don’t like. But, it’s really down to personal preference here on what makes it easy for you to read. Unfortunately, the washers are an unusual size and there is no light indicator showing you if it is on or off.

 

You should consider this one if you have a bigger tank, with more stock.

Pros

  • Solid build
  • Easy to adjust bubbles
  • 2-year warranty
  • Reliable output
  • Quiet
  • Can use with large or small cylinders

Cons

  • No manual (simple to set up though)
  • Uncommon washer size

AQUATEK CO2 Regulator Mini

Features:

  • Dual gauge
  • Needle valve
  • Solenoid valve
  • Bubble counter
  • Integrated check valve
  • Gauges read 1500 psi and 200 psi

 

Including most of the kit you need to get started, this mini CO2 regulator is best used with smaller tanks, and is compatible with common diffusers and atomizers. It doesn’t require an adaptor to connect a standard 24oz CO2 cylinder.

 

It’s reliability has a mixed reception. Some people claim it’s difficult to set your ideal bubble rate, but once you find it, it stays consistent; others claim it is constantly changing.

 

The overall build quality isn’t for me, I prefer a solid build of either stainless steel or brass. This is made from a mixture of plastic and steel, which decreases its overall durability. The solenoid valve is cheap and made in China, however, it does use a light indicator.

Pros

  • Include bubble counter and integrated check-valve
  • Gauges are easy to read
  • Light indicator

Cons

  • Not the best build quality
  • Unreliable output
  • Cheap solenoid valve

Up Aqua CO2 Regulator

  • Dual gauge
  • Solenoid valve
  • Needle valve
  • Gauges read 3500 psi and 140 psi

 

Very durable, it’s made from heavy duty brass, so it’s built to last. The needle valve needs some fine adjusting, but once you’ve found the spot, it provides a consistent, reliable output.

 

Featuring an adjustable valve, is a must if you want to use this for multiple tanks.

 

The electric solenoid valve is excellent quality, but does a “break-in” period of a few weeks. You’ll need to buy the bubble counter, check valve, and other equipment necessary. But, the good news is, it’s compatible with most.

 

A good option if you have a larger tank.

Pros

  • Reliable and consistent output
  • Very durable
  • Easy to use
  • Includes manual
  • Compatible with US standard CO2 cylinders

Cons

  • May go through a “break-in” period

SR Aquaristik Aquarium Dual Stage CO2 Regulator

  • Dual stage valve
  • Dual gauge
  • Bubble counter
  • Solenoid valve
  • Needle valve
  • Gauges read 3500 psi and 140 psi

 

If you want an affordable dual stage regulator, this might be the one for.

 

Highly reliable, the needle valve isn’t very sensitive, making it easier for you to get a precise bubble count and flow rate. The solenoid is very good, and it comes with a nice LED light so you can clearly see when your CO2 system is off and on.

 

The gauges are clear and easy-to-read. Because it’s dual stage, not single stage like the others, you get a more reliable and consistent CO2 output.

Pros

  • Dual stage (adds safety)
  • LED on/off indicator
  • Reliable and consistent
  • Easy to setup and use
  • High build quality

Cons

  • More expensive than the others, but it is dual stage not single stage (you get what you pay for)

Final Thoughts: Which is The Best?

Look, when it comes to CO2 regulators, you tend to get what you pay for. The best and most reliable CO2 regulators are going to cost a lot.

 

If you’re new to the hobby and want extra safety, don’t look past the dual stage regulators. The SR Aquaristik regulator provides outstanding value for money.

 

Happy fish keeping!

Christopher Adams

Hey there, my name is Christopher and I'm the creator and editor of this site. I've owned successful aquariums for the past 23 years. My mission is to educate, inform, and entertain on everything that's fish.

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