CO₂ diffusers are characterized above all by their ability to atomize the gas very finely. This increases its solubility in the aquarium water and makes the CO₂ supply more efficient. But what if the diffuser doesn't work properly? Here we point out some typical situations with diffusers. We go into the conditions for newly bought and already existing dosing devices in particular.

Disrupted bubble formation with a newly bought CO₂ diffuser

Especially with newly purchased products, you naturally expect them to work flawlessly. A freshly installed diffuser sometimes needs a few days, however, until it has properly "settled in". Below we describe the most common problems with newly bought CO₂ diffusers.

Bubbles too large

With freshly installed diffusers, operation may not be quite optimal in the first few days. Give it some time here until the membrane and the body of the diffuser have fully soaked up water. As a preparatory measure, you can certainly put such diffusers in a water bath for a few days before putting them into operation in the aquarium, to shorten this process.
Especially with dosing devices with a replaceable membrane, such as most stainless steel diffusers, very large bubbles otherwise form in the beginning. You should also let the CO₂ diffusers from the manufacturer AQUARIO soak up water beforehand.

Hardly any bubbles, or only at one particular spot on the membrane

If bubbles don't come out of the CO₂ diffuser across its whole surface (quite often only at one particular spot at the edge of the membrane), there is very likely a pressure problem with the CO₂ system. Dosing devices like a diffuser in particular require a high working pressure (usually above 1.5 bar), because by design the membrane is a fairly strong obstacle for the gas passing through it. But that is the only way to achieve fine atomization. If you have this problem, increase the working pressure at the pressure reducer of your CO₂ system. Note: Certain pressure reducers are not able to adjust the working pressure. If the factory pressure is not sufficient here, the pressure reducer is not well suited for operation with a diffuser. One solution is to switch to a different CO₂ pressure reducer or to use a dosing device that needs less working pressure (for example a Flipper or Paffrath bowl).

No bubbles at all

If no bubbles come out of the diffuser at all, there can be several reasons. Was the diffuser only just connected? Then give it a little more time. It can sometimes take several hours for a reaction to occur after an adjustment on the CO₂ system. There is simply a certain time lag.
If all parameters such as the CO₂ cylinder valve, cylinder and working pressure and the needle valve setting have been checked and are correct, a leak may be the cause. Here the gas takes the path of least resistance. So check all connections and fittings again carefully. We explained how to find a leak easily in this article.
Another possible cause could be a clogged component of the CO₂ system, such as the check valve. Please check all the installed individual parts in the tubing run one by one to identify the possible culprit.

Disrupted bubble formation with an older CO₂ diffuser

With CO₂ diffusers that have been running for a longer time, it is normal for them to lose efficiency over time. The reason is often dirt or algae deposits forming on the membrane, which clog it and make it less permeable. It is therefore important to clean the dosing devices regularly. We described exactly how to clean CO₂ diffusers in this separate article. As a rule, this is done quite simply and effectively by soaking the affected parts in a bath of chlorine bleach.

If bubble formation still malfunctions despite a cleaned diffuser, other causes can play a role too, such as a leak in the system or clogged or defective other components of the CO₂ system (for example the check valve). In many cases, the CO₂ cylinder has also simply run empty. Please look at the "No bubbles at all" section above to see which other sources of error you can check and eliminate.