Where to put the check valve on an aquarium

Ever wonder, “Where do I put the check valve on an aquarium?” let alone how to use a check valve in an aquarium? I’ve seen some confusion around this topic quite often and I can relate, I still remember when I installed my first check valve. In this quick write-up I’ll go over some dead easy instructions on where to put your check valve for your aquarium.

Airline tubing

Locate your airline tubing, it’s the clear tube that is supplying air (whether CO2 or O2) towards your tank.

Check valve

With the check valve in your hand, figure out which way is out and which way is in. This can be done by simply blowing into one end of the valve until air can pass through (trust me you’ll know). Take that side you were just blowing into and attach it to your air source via airline tubing.


In the following diagrams are examples a CO2 setup or air pump + air stone:


When attaching your check valve, you’ll want to make sure you do it right. Because you are essentially protecting your hardware, in many cases an air pump or even more expensive…your solenoid/regulator for CO2.

Since check valves can be bought at a relatively cheap price, I’d recommend buying 2 and placing them on the different locations of the airline tubing. Another tip is to place your air supply higher than your aquarium.

Now, I can’t guarantee that any of these tips will 100% prevent back-flow into your devices but, they will decrease the chances of it happening.


So in short, take the check valve, blow into it. If air can pass through, take that side attach it to the tubing coming FROM your air source. Attach tubing to the other side of the check valve and attach your air stone or CO2 diffuser on the end of that side.

Until next time, keep your thumbs aquatic!

Where to put the check valve on an aquarium
Article Name
Where to put the check valve on an aquarium
Here is the proper way to install a check valve into your aquariums airline hose (applicable to CO2 as well)
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The Good Algae
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