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Whisper quiet air pump

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simon_the_plant_nerd

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I need to get an air pump that is as silent as it gets. I want to add it to a timer for night time oxygen but may also use the same for a sponge filter in a nano tank if it’s quiet enough.

Anyone recommend something? The air output doesn’t need to be high at all as they’re both small tanks.
 
dw1305 said:
Hi all,

The piezoelectric ones are quiet.

cheers Darrel
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Well, I didn’t know such a thing existed. I’m surprised the deflection in a piezoelectric actuator is substantial enough to move much air. It must be running at or near mains voltage to do much.

I’ll order one and report back.
 
simon_the_plant_nerd said:
Well, I didn’t know such a thing existed. I’m surprised the deflection in a piezoelectric actuator is substantial enough to move much air. It must be running at or near mains voltage to do much.

I’ll order one and report back.
Click to expand...
Well, if it is actually below 33db and puts out a decent amount of air, I might consider one myself. The video made it 'look' good but keen to hear what you think @simon_the_plant_nerd !
 
I have a Rosewood q1 nano air pump, it's one of the piezoelectric ones.
Yes, they are that quiet!
No vibration either so can be fixed to the side of the tank.
I ran an airstone off mine or a small sponge filter but didn't think there was enough air pressure to run both.
 
Also depends if you want a plug or usb.
I had the Nicrew one in this image, that is really quiet but uses a 3 pin plug.
I swapped it out for the USB one in the image.
Weirdly the usb one is essentially twice as powerful, despite being lower power.
The USB one is a bit louder though. Still can only hear it if I put my ear close to it.

FYI with a splitter you could run a couple of stones off that one usb pump. So a few of them may do what you need.
 

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Little said:
Also depends if you want a plug or usb.
I had the Nicrew one in this image, that is really quiet but uses a 3 pin plug.
I swapped it out for the USB one in the image.
Weirdly the usb one is essentially twice as powerful, despite being lower power.
Click to expand...

The deflection in a piezoelectric actuator is proportional to the voltage applied. USB is 5V (usually) whereas mains voltage is 230V so I’m assuming that the three pin plug is required to supply sufficient voltage to move the actuator enough to move air. I’m speculating as I’ve not seen one of these pumps in person (yet).

An ordinary air pump uses electromagnetism to actuate a mechanical switch which moves a diaphragm to move air. These can be operated at lower voltages like what is supplied from USB. The mechanical components create a lot of the noise so this is why a piezo based design could be a lot quieter.
 
Mine – NICREW – just arrived and is very quiet, as in silent. It isn't adjustable and the flow of air is medium, not strong, but they are a real boon. I wish I'd known about them earlier. Another great Darrel tip.
 
I’ve been looking for a more silent air pump and had no idea that these existed! None for sale around here that I could find, so I just bought 3 different ones from Aliexpress for cheaper than I would pay for a slightly less noisy normal air pump in any LFS. Hopefully at least one of them works.
 
AlecF said:
Mine – NICREW – just arrived and is very quiet, as in silent. It isn't adjustable and the flow of air is medium, not strong, but they are a real boon. I wish I'd known about them earlier. Another great Darrel tip.
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How big is your tank? I tempted to a few for my tanks. Like two in each 150 L.

Cheers,
Michael
 
I have a 100L. I had 2 sponge filters – in addition to a fluval 107 – and decided to remove one sponge and replace with an air stone, so I have more room for planting. The device is very easy to stick to the side of the tank and comes with an air stone. Two would work. I'm not sure if you could run 2 air pumps off one, as I do with my standard pumps. But if I could I'd replace all my humming pumps with these.
 
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Not sure if it’s worth noting, I use a fan speed adjuster on the little usb pump to slow it down even further.
The air restriction valves slow them but do not also quiet them in the same manner the fan speed will do.
If the Nicrew is not strong enough you can get a middle ground of sound and performance of the usb pump on a controller.
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I bought the Interpet NeoAir Nano for £17.99 including delivery.

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I chose this over one of the many Amazon unknown brands as I could buy it from a reputable retailer and like having a warranty I can claim on. I’ve had trouble with Amazon recently and claiming on warranties.

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The packaging is quite nice if a bit of a puzzle to get into. Inside there is the pump and power supply. These are hardwired together so if you want to thread the cable through a hole in a cabinet you may have difficulty. The cable is 1m long approximately.

It also comes with a wee bracket to hold it to either the glass by suction cup or to the cabinet or a wall with included screw and washer. It also has foam feet so it can sit flat on a surface. Printed instructions are included which is nice.

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It’s small, as expected. The power supply is also small. If you were to open it up you would find a printed circuit board with what looks like two large resistors, a capacitor, a smaller resistor (presumably for discharging the cap) and what looks like a thermistor. You would also find that the output side of the circuit board is 120v AC to drive the piezoelectric actuator, stepped down by the big resistors and smoothed by the cap I suppose. Obviously I didn’t open it up as that would invalidate the warranty, but if you did, that’s what you would find.

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Here it is sat next to an APS AP-2B, a typical diaphragm based pump (this has two diaphragms to run two air stones). It also has a battery in it which is kind of nice but obviously adds some size and weight.

For noise comparison I used two methods: Method one, a free iPhone app. Method 2, my wife’s ears.

Method 1:

Ambient noise in my living room:

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Just the general background level. No particular sources of noise, just my dogs breathing and the hum of the central heating.

With the APS pump on connected to 500mm of silicone hose via a check valve pumping into a 25l tank. Measured with microphone from 250mm away from the pump.

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Swapped the pump for the Interpet NeoAir Nano. Everything else the same:

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The iPhone app says that’s significantly quieter. I can’t verify the app’s precision but it’s definitely a lot quieter.

Method 2, my wife’s ears test.

“That’s LOADS quieter. The other one was doing my head in.”

She also remarked that she could only hear the bubbles in the tank now and not the pump. I agree. With my ear pressed to the pump I can hear it vibrating. At 1m away, it’s inaudible. Just the soothing sound of bubbles in the tank.

Air output is more than sufficient for the tank size quoted in the instructions. I’m going to use it for supplementary oxygen and will be running a filter anyway which provides some surface agitation so in my larger tank, it will be perfect. The APS pump is definitely giving out more bubbles which I expected but the trade off for silence is more than satisfactory.

In summary, it’s whisper quiet. Very pleased with it. 👍🏻

EDIT: found these videos on YouTube while looking at how the pumps work:





The check valves inside the housing which allow air to build on both the positive and negative peaks of each cycle are a nice design.
 
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I bought 3 different models from Aliexpress and they all came as 220-240V, despite it being announced as 110-240V. Do you think I could buy a simple 12V power source and replace it? Do piezoelectric pumps work with DC current? It doesn't specify it. I could cut the wire and test the voltage, I suppose, but I would rather have some reassurance.

The seller said I could just use 127V, but from what I can see it is way too weak. It barely works with an airstone and only if it is very close to the surface.

Edit: I think that it makes no sense for a piezoelectric equipment to work with DC. I don’t really know the details of how it works, but from what I imagine, it would need to be powered with AC and a high voltage and frequency. So I won’t be trying to replace the power source and instead I bought a small voltage transformer. It sounds like something that I should have at home, anyways.
 
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LMuhlen said:
I bought 3 different models from Aliexpress and they all came as 220-240V, despite it being announced as 110-240V. Do you think I could buy a simple 12V power source and replace it? Do piezoelectric pumps work with DC current? It doesn't specify it. I could cut the wire and test the voltage, I suppose, but I would rather have some reassurance.

The seller said I could just use 127V, but from what I can see it is way too weak. It barely works with an airstone and only if it is very close to the surface.

Edit: I think that it makes no sense for a piezoelectric equipment to work with DC. I don’t really know the details of how it works, but from what I imagine, it would need to be powered with AC and a high voltage and frequency. So I won’t be trying to replace the power source and instead I bought a small voltage transformer. It sounds like something that I should have at home, anyways.
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A piezoelectric actuator moves due to the changes in amplitude in the driving signal so an alternating current would be required. If supplying from DC you would require an inverter circuit.

The displacement of the actuator (ie how much it moves) is proportional to the voltage. The one I bought uses 120V to operate which is reduced from the mains 230V by way of two resistors and a capacitor. If supplying from 12V you would need a boost circuit to achieve sufficient movement.

So although it would be possible to supply with 12V dc using an inverter and a step up circuit, it would be inefficient and add complexity.

Why do you wish to do this? Battery backup?

EDIT: just reread what your edit. Your method seems best. Inside the power supply (assuming it’s been built correctly) should be some sort of overcurrent protection. In the case of the interpet model I bought there is a small thermistor. Also some signal smoothing to prevent transients damaging the actuator. By removing that supply and connecting directly to 127V mains you forego that protection. The pump would operate but potentially fail under fault conditions.
 
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