When it comes to reducing the air flow in your aquarium, the most popular solution is to use an idle air control valve.
But it may surprise you to learn that this valve could be doing your tank more reproductive harm than good.
So read on to learn more about aquarium airline control valves and, perhaps most importantly, my recommended way of controlling the air flow.
What is an airline control valve
An airline control valve is yet another fitting that can be installed on your airline tubing.
As the name suggests, this valve allows you to precisely control the flow of air in your aquarium…
And how the valve works is actually quite clever…
In its simplest form, a flow control valve is little more than a tube with a screw in it.
If you unscrew the valve all the way, air can freely move through the pneumatic valve without restriction…
As you begin to turn the screw, it begins to block off the airline.
The more you turn the screw, the smaller you make the gap through which air passes…
To put it simply:
Large gap = stronger airflow
Small gap = weaker airflow
I would like to add that idle air control valves will not completely close, as this would put too much pressure back on your air pump, potentially damaging it.
Even when “fully closed,” a small amount of air will still be able to move through the air control kit.
Types of airline control valves
It may surprise you to learn that airline control valves are actually available in a variety of styles…
Straight control valve
This will be the airline control valve that you are most familiar with. Straight valves are commonly available both online and in local fish stores.
Elbow control valve
If you have ever tried to bend plastic airline tubing at 90 degrees (L-shape), you know you will more than likely put a kink in it.
Ordinarily you would use an elbow airline connector to get around this problem.
Well, an elbow control allows you to both bend the tubing and control the air flow in a single fitting: a 2-in-1 fitting!
Metal airline control valves
Airline circuit control valves are also available in a metal sleeve design – brass or steel.
Instead of a screw, metal control valves use a lever to adjust the flow…
If you do plan to use an airline control valve after reading this article, then I recommend going the plastic route. My experience with metal airline control valves has not been pretty – they are prone to rust and corrosion.
Fishlab Tip If you want to control airflow on two or more air tubes at once, you can use a gang valve – a single airline fitting that can take the place of multiple control valves.
Why do you need an air control valve?
While fully featured aquarium air pumps are equipped with a built-in flow control knob (called a rheostat), cheaper or battery-operated models do not have the same luxury.
In this case, you will need to come up with a solution to control the airflow yourself, particularly if the default airflow is too strong for your aquarium…
Let’s say that your airstone is producing too many bubbles; you could use a flow control valve to reduce the amount of air flowing through the tubing. Less air reaching your airstone means fewer bubbles.
Alternatively, your air-powered sponge filter may be creating a water current that is too strong for your fish – reducing the air flow via the accurate control will slow down the rate at which water is drawn through the filter.
Same goes for any other air-powered equipment you use in your aquarium.
To put it simply, if you need to control the air flow rate on your aquarium, this little valve will be your best friend.
Problems with using an air control valve
There is no arguing that an 2-position air control valves are the most popular way to regulate airflow.
Many aquarium air pump manufacturers even recommend using an air control valve in their instruction manual.
However, restricting airflow in this manner does have an inherent problem…
It increases back pressure!
You see, the smaller the hole in the valve, the harder your air pump has to work in order to force air through.
This extra work can seriously reduce the service life of your air pump, causing the diaphragm inside to tear prematurely.
It is for this reason that many hobbyists use a bleed valve instead.
A bleed valve allows you to reduce the airflow without the extra back pressure.
If you want your aquarium air pump to last as long as possible, this really is the best way to control the air flow in your aquarium.
Want to know more? Check out our bleed valve guide.
Do you use an air control valve in your aquarium? Let me know in the comments below!