Home > Aquatics > General Forum > How air pumps work and problems you encounter

How air pumps work and problems you encounter

Feb 09, 2013
David agent wrote
Air Pumps and why yours isn’t working properly or is making too much noise

Well, the Air Pump is the most popular way of introducing oxygen into the aquarium, running an undergravel filter or bubble wall, or working an action ornament.

Without appearing to be “teaching granny to suck eggs” let me explain simply how they work. They all rely on our alternating electricity supply to make an arm move backwards and forwards slightly with each change of cycle. This arm is attached to a rubber diaphragm which is then attached to the valve block. Air from outside is allowed into the block on one cycle and pushed out down the airline on the next cycle (this is why they all “hum” when running as this happens 50 times a second!)

And it is the diaphragm being moved by the arm which sucks air in and then pushes it out. So it has to work hard when pumping air and it is why it doesn’t always last that long. Once it gets a split in it, (or the “flappers”, which ensure air comes in one way and out the other, get worn) the arm can then swing further and quite often physically hit another part of the internal workings, thus making the metallic rattling noise

In an attempt to make the diaphragms last longer here are a few tips :

1. Always keep the Air Pump above tank water level if possible. Or leave a loop of airline a couple of inches above the water level, or better still use a non-return valve (also called a check valve) (see here : http://www.aquatics-online.co.uk/catalogue/airstones-airline-accessories-g58-281.asp ) These stop the tank water siphoning back out of the tank when the pump is switched off, into the Air Pump with fairly obvious electrical safety issues!

2. Use an Air Pump of roughly the right air output to supply air to whatever you are hoping to run from it. For example a long bubble wall will need much more air than a single airstone.

3. Check and if necessary replace your airstones (irrespective of whether they are ordinary ones, ceramic, wood or walls or discs) regularly. All these types of airstones do get blocked internally after a while, and this puts back pressure on the Air Pump diaphragm

4. Don’t force your Air Pump to push air down to too great a water depth. Just check that the air flow from the open air pipe is adequate before attaching the airstone or whatever. Again this will exert an extra load on the diaphragm

5. If you use a double outlet Air Pump, try not to use both outlets joined into one ordinary airline. “Two into one doesn’t go”: it will result in your diaphragms not lasting as long even if it does appear to work

Most manufacturers do supply replacement diaphragms and valves but sometimes only in a Service Pack of all the replacement parts (see here : http://www.aquatics-online.co.uk/catalogue/air-pump-spares-g55-280.asp ) They are relatively easy to change, once you have disconnected the Air Pump from the mains electric (Health & Safety!!) and opened up the casing.

And finally : the “humming”. As I mentioned earlier, all Air Pumps make this noise : its how it works. (Better quality Air Pumps have better engineered internals and a thicker walled casing so making the noise appear less). Perhaps you should open it up and check that there is nothing loose inside, the diaphragms are not split, the “flappers” are clean and fitted over the inlet/outlet holes, and the arm hinges are good. If all appears OK then you will have to live with it! Or buy a better quality one (see here : http://www.aquatics-online.co.uk/catalogue/air-pumps-aerators-and-spares-g54-279.asp ) And whatever you do don’t wrap it up in an attempt to deaden the noise : it could stop the air from getting into the inlet, overheat the Air Pump causing it to catch fire and burn down your house, the neighbours houses, the United Kingdom, and the World!! (Perhaps a bit of an overkill – but you get my drift?)

3 Answers
Feb 11, 2013
David agent wrote
Re the air pump advise, it's all very sound. I appreciate that you are very sensibly erring on the side of safety when you advise not wrapping the pump. However I find that using a piece of 1 inch thick foam, to make a U shaped cradle, does not affect air intake, or make the pump run hot, but it does provide a very noticeable reduction in the sound emitted.

Cheers Noel
Feb 11, 2013
David agent wrote
In my opinion Air Pumps are a total waste of time, (only any good for small tanks) I would always recommend using power filters, with a surface skimmer attached to the intake and have the spray bar placed just submerged at the surface of the water. I've run my 7' X 2' X 3' tank like this for over 25 years without any problems. Have a good day.

Keep warm .... Kev
Feb 11, 2013
David agent wrote
Hi that is why I only ever use piston driven air pumps which do not hum and do not have a rubber diaphragm. I have six in use and each one is over 8 years old they cost twice as much as standard air pumps but out last them 10 to 1 easily.


Editors note... I did ask which Brands... but the labels have come off!