Glass CO2 Check Valve

• Prevents water back-flow / siphon.
• For 4mm internal diameter tubing.
• Made of crystal clear glass.
• Easy to installation.
• Attractive design.
• Comes with 2 x suction clips

Without a check valve in place, when the flow of CO2 is turned off (e.g. overnight when it's not needed) water can siphon down the tubing from your aquarium and enter your solenoid, causing it to flood, which may damage it, or require maintenance to dry out the water.  This simple item eliminates that possibility by not allowing air or water to flow in the opposite direction to which it is installed.

Because the item is made from glass it is inherently delicate, and extra care needs to be taken when attaching the tubing. It is highly recommended that the tubing is first warmed in freshly boiled water to soften the tip when pushing onto the diffuser inlet.

This unit uses gravity to operate, it must therefore be aligned in an upright/vertical position - as shown in the picture.

Looking at the valve, you will notice that one end is slightly more tapered (narrower) than the other. It may also have a faint line running about around the tapered section - this is the inlet and should be at the bottom. To verify; while holding the valve in a vertical position, you should not be able to blow down the outlet. If you can, you've got it the wrong way around.

Push CO2 tubing onto corresponding inlet/outlet as far as you can.

Tip: Softening the tubing in freshly boiled water will make it easier to push the tubing onto the valve.