UNS Pro Inline CO2 Diffuser

UNS Ultum Nature Systems Stainless Steel Aquascaping Inline CO2 Diffuser Freshwater Planted Aquarium Tanks

$31.99 USD

Usually ships in 1-2 business days from our fulfillment center

IMPORTANT: If your order arrives damaged, please take photos and contact us right away—we’re here to help. Due to the nature of certain products, returns are subject to approval. For full details, please visit our FAQ.

The Ultum Nature Systems Pro Inline CO2 Diffuser provides clean, consistent CO2 diffusion while keeping equipment outside of the aquarium. Designed for use with canister filter outflow tubing, it’s a top pick for planted aquarium hobbyists who want efficient CO2 distribution and less equipment inside the tank.

Available in multiple sizes to fit common aquarium filter tubing, the UNS Pro Inline Diffuser features a side-mounted ceramic disc. This small detail reduces flow disruption and makes it easy to clean or replace when needed.

Product Highlights
- Reduces clutter and visible in-tank gear
- Fine CO2 diffusion and even distribution
- Side-mounted ceramic disc made from PC material is durable for long-term use and positioned for simple maintenance and replacement
- Available in three common sizes to accommodate a range of canister filter setups

Inline diffusers are designed for use with pressurized CO2 systems and external canister filters. Ceramic diffusers naturally accumulate buildup over time and may require periodic cleaning or replacement to maintain consistent diffusion performance. The image below depicts where to install it and how it works.

UNS Pro Inline CO2 Diffuser installation guide for planted aquarium tanks and aquascaping

Compatibility Guide


Model	Tubing Size	Compatible Filters
12MM	OD: 16mm / ID: 12mm 1/2" Tubing (12/16mm)	UNS Blitz 32oz UNS Delta 60 UNS Delta 90 ADA Super Jet ES-600 Eheim Classic 2213 Use with Aquario Neo Flow MEDIUM accessories
16MM	OD: 20.5mm / ID: 15.5mm 5/8" Tubing (16/22mm)	UNS Delta 120 Use with Aquario Neo Flow LARGE accessories
20MM	OD: 25mm / ID: 20mm 1” Tubing (20/25mm)	Compatible with larger canister filters such as the Eheim 2262

Important Information:
- For use with pressurized CO2 planted aquarium systems
- Designed for inline installation with canister filter tubing
- Replacement ceramic disc available separately

UNS Pro Inline CO2 Diffuser for healthy aquarium plant growth and aquascaping

Ultum Nature Systems creates premium aquarium products designed by hobbyists, for hobbyists. Known for thoughtful design that first appeared in their line of rimless aquariums, they continue to move ground in the industry, with the health of your aquarium always at the forefront. Since the release, the brand has expanded into a variety of aquarium needs and everyday essentials that fuse form and function.

From best-selling substrates like Controsoil and Controsand to powerful filtration systems and nutrient-packed aquatic plant fertilizers for aquascapes at every stage, you're sure to find something you didn't know you needed. Jump further in and browse CO2 gear, various natural hardscape choices, then pick up some live aquatic plants and the tools you need to plant, maintain, and keep your tank looking its best. With a recent venture into the world of marine, UNS supports today's aquarium hobbyists every step of the way.

Inspired by nature and powered by the art of aquascaping, plan your next aquarium project with Ultum Nature Systems today.

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Ultimate Planted Aquarium CO2 Guide

Adding CO2 to a planted tank might seem complicated at first—with all the gear and technical terms, it’s easy to feel overwhelmed. However, once you understand the basics, setting up a CO2 system for your planted tank is just as straightforward as setting up a filter or light. We’ll walk you through everything you need to know step-by-step.

Aquario Neo CO2 Diffuser Normal Large injecting micro CO2 bubbles

What is CO2 and why is it important in a planted aquarium?

Just as we need oxygen to survive, aquarium plants rely on carbon dioxide to thrive. CO2 is naturally produced by fish, humans, and other animals, providing plants with what they need. In a freshwater tank, fish naturally produce small amounts of CO2, which can give the impression that some aquatic plants don’t need it. In reality, all plants require it, just at different levels. This is why CO2 injection systems are strongly recommended—Popular beginner plants like Anubias, Bucephalandra, Java Fern and aquatic mosses are commonly labeled as “low-tech” because they can handle minimal levels. However, even hardy plants benefit greatly from added CO2 and will grow more quickly and vibrantly with it.

Aquascaper’s Notes: During photosynthesis (lights on), plants release oxygen, which helps keep the water well-oxygenated for livestock. As a result, most aquascapers skip traditional airstones or bubblers.

Easy beginner low light aquarium plant Java Fern Trident

Microsorum pteropus AKA Java Fern 'Trident' producing oxygen

Okay, so aquarium plants need CO2, but what does it really do?

For proper growth, aquatic plants require a balanced mix of light, nutrients and CO2. Think of it like a pie—each slice represents one of these elements. If any slice is too small, large or missing, the pie is incomplete and represents an imbalance aka ideal conditions for algae to take over. Injecting CO2 into a freshwater planted tank improves plant health, and stability. That’s why we recommend CO2 systems even in low-light or beginner-friendly tanks. It completes the pie, creates balance and reduces the risk of algae problems.

Common examples of planted aquarium imbalances:

Too much light, but not enough CO2 or nutrients
Too much nutrients, but not enough CO2

What equipment do I need to start injecting CO2?

The process is simple, once you understand must-have gear. Here are our four essentials every planted tank hobbyist should have.

1. CO2 Regulator

Controls overall output levels. Each regulator will have at least one gauge that will display the maximum output pressure. We typically set this anywhere between 25-40PSI (safe range) on the main valve and fine-tune the flow with the needle valve (the smaller one) to dial in levels being injected. Dual-gauge regulators show both working pressure and available gas reserves in the cylinder. Higher-end models may also include a solenoid. A solenoid lets you shut off CO2 manually or with a timer—usually synced with the lights, since aquarium plants will not require it when lights are off.

Shop UNS Mini CO2 Dual Stage Regulator CO2 - Glass Aqua

Almost all CO2 regulators will have a gauge that displays maximum output pressure

Shop UNS Pro CO2 Dual Stage Regulator CO2 - Glass Aqua

While other CO2 regulators will have dual gauges

Main pressure valve on an Ultum Nature Systems Mini CO2 Regulator

Needle Valve on an Ultum Nature Systems Mini CO2 Regulator

Ultum Nature Systems UNS Dual Gauge CO2 PRO Regulator for Planted Aquariums

CO2 Regulator solenoid example

2. Cylinders & Cartridges

These store CO2. How long do they last? This is one of the most common questions we get—and the honest answer is: it depends. Every aquarium is different. Factors like tank size, aquarium water chemistry, plant variety, plant density, and CO2 injection levels needed all impact how quickly a cylinder or cartridge is used up. Here are some guidelines:

Cartridges: Single use, compact and convenient. They are the perfect desktop solution for nano tanks between 1 - 8 gallons.
Paintball Cylinders: Budget-friendly option that is popular for convenience, size and ease of use. Most can be refilled at related hobby (paintball) stores. A great option for aquariums up to 20 gallons.
Standard CGA-320 Cylinders: Don’t let the name intimidate you! A CGA-320 is a North American standard that can be refilled at most welding, air-supply or local brewery shops. This is our top recommendation for all aquascapers who are invested in the planted tank hobby. This type of cylinder holds the most and will require less refills in between uses.

Planted Aquarium CO2 Injection Equipment

3. CO2 Diffuser

Delivers CO2 in the form of ultra-fine bubbles into the aquarium. Some aquarium airstones may look similar to CO2 Diffusers, but these aim to produce larger bubbles for surface agitation and gas exchange. The larger the bubbles, the more the aquarium will be oxygenated. CO2 needs to be easily dissolved in a planted aquarium, which means the smaller the bubbles, the better.

4. CO2-Proof Tubing

This is important. Normal airline tubing for aquariums cannot handle the higher pressure of CO2 systems. Specialized CO2 proof tubing is built to withstand pressurized CO2 and allows it to travel safely into an aquarium without leaks.

Ultum Nature Systems Pro CO2 Tubing | Planted Tank CO2 - Glass Aqua

Optional CO2 Equipment

1. Bubble Counter: Not required, but a helpful tool! Bubble counters provide a visual reference in the form of bubbles for how much CO2 is being injected into the tank.

2. Drop Checker: This small glass accessory hangs on the rim of the tank or suctioned to a glass panel inside the aquarium. They typically include a liquid solution that changes colors based on the amount of CO2 injected.

Yellow means too much CO2, blue indicates too little, and green means the levels are just right. It can take a few hours following installation or a water change to change colors!

Ultum Nature Systems Micro CO2 Bubble Counter | CO2 - Glass Aqua

Ultum Nature Systems UNS CO2 Drop Checker

If you’ve read this far, we hope you now have a better grasp on planted aquarium CO2 injection. If you’re still not sure and a full setup feels like too much, we recommend starting out with a simple CO2 Kit. It’s easy to use, beginner-friendly and great for many tanks! But if you’re ready to make that leap and full send into CO2 injection, check out our bundled CO2 Kits at discounted prices. As always, if you have any questions, our team is always happy to help!

Shop Planted Tank CO2 Kits

Overall rating: 5.0 / 5 from 6 reviews.

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Reviews

A definite upgrade

"I was happy with my first CO2 diffuser, the standard-issue Aquario Neo model. It did a good job, but I felt that too many CO2 bubbles were escaping to the surface. That prompted an upgrade, to the UNS Pro Inline diffuser. The bubbles are definitely finer, and they make it all the way across the tank before dissipating. The plants love it, and I do too!"

— John M. (5/5)

UNS inline diffuser

"nice inline diffuser, no complaints whatsoever on it. bubble size is fine. would recommend"

— marco e. (5/5)

Great build quality and performance

"I'm very happy with this so far. At the same rate on my bubble counter I'm getting much greater CO2 diffusion with the this inline diffuser compared to the in tank bubbler I was using before. Very happy with the build quality as well, fits together perfectly with the UNS tubing."

— Daniel S. (5/5)

Great diffuser

"Love the very fine bubbles you can barely see great for hobbiest that don't like to see all that co2 bubbles and the built of the diffuser is very good quality material"

— Joel Z. (5/5)

"Easy to install, looks fancy and works great. Super small bubbles 🫧"

— Roger (5/5)

"La burbujas son finas casi ni se ven en el acuario como si hubiese un reactor de co2"

— bronaldo (5/5)

Q&A

I use a spray-bar for my outflow that i have angled upwards to cause surface agitation. Can i use this with that kind of outflow or do i need something else? Basically wondering if that will send my co2 bubbles straight to the surface and out of the tank: Hello and thanks for your interest, in short, using the UNS Pro Inline CO2 Diffuser with a spray bar setup would not be the most ideal setup since it would now allow all of the CO2 to dissipate into the aquarium. This is especially true if you have your spray bar positioned upwards. We would recommend taking a look at other outflow options we provide from Aquario such as the Aquario Neo Flow Premium lily pipes if you are using a canister filter. You can find that here: https://shop.glassaqua.com/products/aquario-neo-flow-aquarium-lily-pipe-premium-set?variant=39335907164246 we suggest this option since it does provide a gentler flow and surface skimming. If you would be open to just swapping your spray bar for an alternative outflow option, each of the Aquario Neo Flow add-ons are available on our website as well by searching "AQUARIO NEO FLOW". Hope this helps!

Shipping
Orders are typically processed within 1-2 business days M-F. However, additional time may be required during peak seasons and federal holidays. For orders containing live plants, we exercise extra caution and assess factors such as travel distance and weather to ensure safe transit.

To avoid delays, please ensure all order information is accurate and complete. We cannot offer refunds and are not responsible for orders shipped to incorrect addresses due to errors in provided information. Once an order has been shipped, delivery times are determined by the carrier and are outside of our control. On average, shipments arrive within 2–5 business days, excluding weekends and holidays. For more information, please visit our FAQ page.

Returns
If you are not satisfied with your purchase, please contact us within 48 hours of delivery. Approved returns must be shipped back within 14 days of approval. Returned items must be unused, unopened, and in their original packaging. Specific return requirements, if applicable, will be listed on the product’s page. For more information, please visit our FAQ page.

Refunds
No worries, we’ll take care of everything as long as it fits the guidelines above.Most answers to general questions can be found on our FAQ page.