What is an Airlift and how does it work?

[Pssymon]

Good day,

In this topic I will explain the basics of Airlift, in particular I will discuss the types we like to use.

What is an Airlift?
An Airlift pump, in essence, is just a pipe placed vertically in a body of water. At the bottom the pipe has an air supply connected, powered by a compressor or an air pump.
The air is forced into the lower end of the pipe, forcing water (and in industrial applications, debris, sand etc.) to the surface.

Usually this technique is used to pump out deep wells in industrial applications, where regular pumps get damaged easily, and to some extent in aquariums.

Many years ago, Marc (the founder of this site) founded the site http://www.koivrienden.com , a Belgian site for Koi enthousiasts.
In collaboration with some members, he started perfecting the Airlift system, minimising its shortcomings and maximising output.
The idea was to perfect the Airlift concept for pond filtering applications.
This has led to the pressure chamber Airlift which has become the cornerstone of what we are working on.

What are the benefits of an Airlift system compared to conventional water pump systems?
In terms of efficiency, the Airlift systems we use cannot be beaten by conventional water pumps by a huge margin.
If you plan carefully when building your pond, you can have ridiculous flow rates at a fraction of the usual energy consumption.

There are some important things you need to keep in mind, as with any system, there are pros and cons.

Pros:
- Energy consumption is really low., making it eco friendly and wallet friendly.
- Capable of huge flow rates.
- Aeration and water displacement at the same time. Your air pump is doing two jobs at once, you could say the water displacement is free!
- Clogging is pretty much impossible with a 110mm inlet.
- The Airlift cannot break down.
- Wildlife or fish can pass through without harm.
- Can also function as a proteïn skimmer.
- Fairly easy to build yourself, if you already have a suitable air pump the Airlift itself is fairly cheap to build and try (Under $40 depending on the parts you have available).

Cons:
- Discharge head diminishes the output rapidly.
- Can only be used in a gravitational pond.
- Works best when the filter area and drains are suitable (small diameters will be a bottleneck).
- Placement. The system has to be dug in to the ground next to the pond.

There are two main types of Airlifts that we are currently using, the Pressure chamber Airlift and the Membrane disk Airlift:

The pressure chamber Airlift:
If you are new to Airlifts or looking for the best efficiency, the pressure chamber Airlift is the best type to start with.
The design is simple but very effective.

Pros:
- Easy to build.
- Low power consumption.
- The most efficient design.

Cons:
- Not perfectly suitable for outputs beyond 20.000 litres per hour.
- Tests show that it becomes really inefficient beyond 24.000 litres per hour.

The pressure chamber design works best with smaller air pumps using low amounts of energy with high outputs.
This Airlift has been tested to an output up to 24.000 litres per hour, at 32 Watt. At this point the efficiency has already dropped considerably, as it can put out 15.000 litres at 9 Watt, 20.000 litres at 12 Watt (same efficiency) and 22.000 litres at 17 watt. This was all measured using the standard 110mm diameter rising pipe.

If you want to find out more, or start building, then I highly recommend watching the 'Airlift: How to build' videos entirely.
After doing this you will know exactly how to build the pressure chamber Airlift. Every detail is adressed in these videos.

You can watch the videos here:

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You can also check this topic about how to build the pressure chamber:
http://www.airlift.eu/phpBB/viewtopic.php?f=126&t=15797


The membrane disk Airlift

Another type of Airlift that some people like to use, is the membrane disk Airlift.
This type of Airlift is a bit more advanced.

Pros:
- Suitable for really high output up to 42.000 litres per hour from a single Airlift.

Cons:
- Requires a bigger pump to operate. Small air pumps lack the pressure required to open the membranes at depth.
- Slight drag due to having to keep the membrane disk open.

The membrane Airlift has been modified and tested many times. More detailed information will be posted in the appropiate section of the forum.
This Airlift is for those applications where huge output is the main goal.

[AndersB]

Thank you for the great information.

All energy consumption is given in watts.
This is a bit confusing as it is related to the efficiency of the pump and dept of the pressure chamber.
In my view it would be more correct to give a liter-per-minute value.
Am I missing something in relation to this ? If not I would like to liter of air demand related to the flow rate in a 110mm pipe.

Thank you for your support.