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If there is one tiny piece of hardware that can save you hundreds of dollars in equipment damage, this is it. When your CO₂ system or air pump is placed below the water line, a natural vacuum forms inside the airline tubing. Without protection, water from your aquarium will slowly siphon backward down the line, creeping directly into your sensitive solenoid, needle valve, or air pump motor. The UNS Advanced Check Valve acts as a literal one-way firewall. It lets gas flow into your aquarium effortlessly, but slams shut the second backflow instantly begins, keeping your expensive equipment dry, safe, and running flawlessly.
Note: A check valve should be installed in-line between your regulator/air pump and your diffuser. For absolute safety, always install the valve upright and pay close attention to the flow direction indicator on the unit during setup.
Fine-tuning your CO₂ setup can seem intimidating at first, but the process is far simpler than it appears. For a safe and reliable introduction, refer to our guide on How to Add CO₂ to Your Planted Aquarium. And if you’re curious about the science behind why CO₂ makes your buce, stems, and carpets thrive, explore The Mysteries of CO₂ in a Planted Tank Explained for a clear breakdown.
Overall rating: 4.8541665 / 5 from 48 reviews.
The UNS Advanced Check Valve is praised for its solid construction and high quality, ensuring reliable prevention of liquid backflow in aquarium systems. Customers also appreciate the fast shipping and delivery of this essential aquarium accessory.
Review topics: ["shipping","quality","issues","works","price","valves","tubing","plants","order"].
"Such an improvement over the check valves I use for air pumps. Absolutely don't want water going back into the CO2 line."
"Great product. Made connecting the two tubes super easy and it was simple to use."
"Shipping from Buce Plant was quick even shortly before the big holidays. The UNS check valve was easy to install and I really like the slimmer size compared to other check valves. I ordered some aquatic plants at the same time and all arrived in great condition and are thriving in my newly setup tank."
"Happy with purchase"
"Hey there! I’m new to CO2, so I got this recommended to keep the water out of my system. The only thing I’m scratching my head about is how to put it together. There aren’t many reviews, and the description doesn’t say how to assemble it. For those of you who are new to this, just a heads-up: make sure the arrow is pointing to your aquarium, or you won’t get any CO2. Also, don’t just stick the whole tubing through it; you need to cut it and attach it to each end. I found this part tricky, especially since it wasn’t in the instructions. But once you get that sorted, it’s all good to go! So, definitely grab it!"
"Works. Great price and fast shipping. I use a small tank and this makes swapping bottles way easier as a bonus."
"Does the job perfectly. Makes changing bottles a bunch easier. Super fast shipping!"
"Great check valve makes disconect and reconect way easier for maintenance"
"This tubing is designed to carry your Co2 into your aquarium. Thick, so your gas does not leach through the hose. Looks high quality. And again, Buce Plant gets the credit for the smooth transaction and the speedy delivery. They also carry black and clear hose in addition to this."
"its a check valve. it works exactly as i expected it to. no issues and good price"
