Flattened tubes are a simple but very good idea for an aquarium aerator to cool a print. Speaking of this, the transformer of my pump is 110VAC, while we’re 220VAC here… I am thinking about adding a diode just to halve the tension but I would have to check if it is that much of a good trick (any idea?)
(via @Hrvoje_Cop_chopmeist )
http://sgabolab.altervista.org/fanless-cooling-system.html
I’m using an Aquarium pump for cooling too (sometimes) https://www.flickr.com/photos/guinthereal/14769101713/
But you need to much pressure if you flatten the tube.
Adding the diode MIGHT work, but doesn’t seem like a great idea… it’ll make the pump see a +340v/0v half-wave input voltage instead of a +170v/-170v full wave input. Could heat up the transformer more due to waveform distortion, could exceed the insulation voltage rating with respect to ground, etc. Really depends on the design of the pump.
@Ryan_Carlyle thanks for the warning! Seems OK as far as I tried (~15 minutes, did not heat significantly). But yes, the waveform is wrong… The pump is well made but has strictly no thermal protection (not even ground line), so I would better keep an eye on it…
Just out of curiosity, is it safer anyhow compared to feeding it 240V directly (no old-school transformers here)? I would guess so but intuition is not a good technical reference when dealing with the mains.
May be I could make a PWM out of an NE555 +RC filter to feed it less power, but here again, I have no clue what I am doing 
3d print your own diaphragm pump.
@Mark_Rehorst I bought it because of the throughput and noise. Looked for the specs again (Tetra brand, Whisper AP150 for 150 gallons aquariums up to 8ft deep): At 24 inches, the AP300 is rated at 2.6 Liters per minute. I think pressure is quite important else the tube will kill the flow
@Stephanie_A you bet I thought about it 
But such pumps are straightforwards and they are made to last… I am not sure I would get some significant advantage (beyond the feeling I made it myself)
I think I would probably just buy a new pump or get a 220:110 travel stepdown transformer rather than messing with mains voltage hacks. That stuff can kill you.
@Mark_Rehorst nice 5 L/min (had to use a converter obviously), but still US norms: no good for me. I need to buy a 240VAC pump now given what I saw when opening the pump – raw electrical without any electronics = no easy way to hack it https://plus.google.com/+JeremieFrancois/posts/CtoGtyuxuQb )!
Just checking… you guys are aware that a normal nozzle blower fan outputs >100 L/min, right?
@Ryan_Carlyle yep but they have zero pressure, i.e. totally worthless for a tube. Now, I do have a 120mm fan fixed to my chassis. It blows a huge amount of air in silence compared to those pesky noisy bulky but nonetheless feeble 30-40mm fans on the average hot end.
But the large one does not blow enough/correctly very close to the nozzle, which is bad (only) with small layers, when the hot end keeps being on top of what needs to be cooled.
This is why I would like to try a “tube fan” (in addition to the existing large fan). It is only a few grams to support compared to the mess required by a regulat hot end fan.
And who knows, it may work 
@Jeremie_Francois I figured that was your thinking. Axial fans aren’t very good for this application.
I really like radial blowers though – I can get such a nice blast of air from a 51mm blower and ~1cm2 duct opening that I usually only run them at 40-60% power. Not sure how that size would do with a long tube though, you might get too much pressure loss.
@Ryan_Carlyle I tried radial fans but mine were noisier (still I like them better as they end up being more efficient imho). The mount is anyway an annoying and significant appendice.
@Mark_Rehorst thanks I would not have tried by fear it blow! I could check that with a scope (and obviously a high voltage non-polarized cap, right?).
FYI My 110V aquarium pump is still working on a diode on 240V, and it does not heat. May be it’s the rewards of having bought a brand for once