# Aquarium air pumps



## black85vette (Jul 31, 2010)

Building a small engine for a friend to go in his office. Looking at some of the aquarium air pumps, some add a comment about how quiet they are. Thought that would be perfect to run a single engine. 

Problem is; what size? Most of them are rated by the size of tank they are for in gallons. Others have a CFM spec on them.  ??? ???

I know this engine will run smooth at 8-10 lbs per my regulator gauge. It has a 1" bore and 1.125" stroke. So anyone have any experience with this? Have a brand or model that would work? Or, better yet the size of tank they were made to use with?


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## shred (Jul 31, 2010)

Hmm.. looks to be about 1 cubic inches. 1728 cubic inches in a CF, right? So if your compressor could put out 1 CFM @ 10 PSI, you should be seeing around 1700 RPM for a single-acting engine. 1 CFM is doable for a big aquarium pump but a quick perusal of the first spec sheets I found I didn't see anything over about 6 or 7 PSI, and that's a $350 Hakko that looks to be designed for monster tanks and stock ponds. 1 PSI is approximately 28" of water, so you'd want a pump that can push however many RPM's-worth-of-CFM-you-need at 24 feet depth of water-- I think that's going to be the sticking point-- look for "high pressure", "high lift" and "deep water" pumps.

[edit: had the cu-in math wrong]


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## Tin Falcon (Jul 31, 2010)

i would do the math and pick out one based on a CFM rating assume that there will be some leakage and that the pump is over rated. 
Typically a compressors is rates at some normal operating pressure ie 4 CFM @90 psi . 
your piston displacement for the sake of argument is 1 cubic inch ( I know it is really .8835......) so if you are running @ 100 rpm @ 10psi g you would be using 100 cubic inches of air per minute @ 10 psi. 1 cubic foot = 1728 cubic inches. so it appears that you do not need a high volume unit. 
Tin


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## Jasonb (Jul 31, 2010)

If you need 28ft of head you are stuffed as even the big koi pond pumps have a max depth of around 10-14ft.

I think you would have to look at piston compressors not diaphram ones is you want any pressure.

Jason


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## don-tucker (Jul 31, 2010)

My brother uses a Nebulizer breathing aid to run his engines,even the 2 cyl paddle steamer engine will run of it,it is not dead quiet makes a putting noise but not bad,just a thought.
Don


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## Tin Falcon (Jul 31, 2010)

the couple of units I saw on e-bay show a 45 liter per minute flow rate that is about 1.5 cfm but the pressure rating is nill. 
Tin


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## Tin Falcon (Jul 31, 2010)

how about the compressor out of an old ac unit or dorm fridge.??
Tin


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## black85vette (Jul 31, 2010)

Tin / Shred. Thanks for the math. I checked the RPM and my tach says 375 rpm at 10 psi.

So, 375 cubic inches per minute (approx) is about .25 cfm (approx)

So my volume is OK if I can get enough pressure. Right?

Tin; a converted compressor would work. It just needs to be "office friendly".  I used to have a small air brush compressor, but it was really loud which was OK for the shop.


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## Deanofid (Jul 31, 2010)

I have a couple of these pumps. Made by Apollo for fish tanks. This one just says 5 watts
on the bottom. It's 3.5" x 5" x 2.5" thick and will run most of my engines.







This engine has a bore of 1/2" and stroke of 3/4". When it's running slow, it's just using
one pump. About the middle of the vid you can see it increase in speed as I plug in the 
second pump.


"http://www.youtube.com/v/5hqMqJeezn...0d0d0&hl=en_US&feature=player_embedded&fs=1">


Dean


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## black85vette (Jul 31, 2010)

Well I got a definitive answer to this. I went down to PetSmart and bought the biggest pump they had.  Two outputs at 4.3 psi each and put in a T to join them.  It will run my EZ engines (which run on breath power anyway) but not my bigger engines.  I will have to admit that it was VERY quiet. Just a faint hum.

While out running around I dropped by Harbor Freight and looked at their smallest air compressors and may just go get one of them. They are about the same cost as the one for an aquarium.


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## Davo J (Jul 31, 2010)

I picked this diaphragm pump up at a yard sale, I was told it was an aerating pump for a sewer tank. It's quiet and has a good air output, but I only use it for our fish tanks. You may be able to find something like this over there.

Dave


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## black85vette (Jul 31, 2010)

Davo J  said:
			
		

> I was told it was an aerating pump for a sewer tank.



Dave; That is real interesting. I have seen a lot of sewer tanks as they are very common around here.  But I have never heard of an aerating pump for one.  Are they common where you are?


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## don-tucker (Aug 1, 2010)

don-tucker  said:
			
		

> My brother uses a Nebulizer breathing aid to run his engines,even the 2 cyl paddle steamer engine will run of it,it is not dead quiet makes a putting noise but not bad,just a thought.
> Don


I didn't mean he takes it away from someone who is trying to breath while he runs his engines :big: he has a spare one.


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## Jasonb (Aug 1, 2010)

The picture of the "sewer tank" pump is also one of the main hakes of Koi pond airpumps, I have had one of their 40lts/sec pumps for a number of years, you can get them upto about 140lts/sec but as i said above pressure will be about 5psi max.

Jason


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## ChooChooMike (Aug 1, 2010)

black85vette  said:
			
		

> While out running around I dropped by Harbor Freight and looked at their smallest air compressors and may just go get one of them. They are about the same cost as the one for an aquarium.



I use one of the H/F paintbrush compressors to run my toys. They are more then adequate for that, but are still rather noisy. Think the one I bought last year was around $75.

Mike


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## websterz (Aug 1, 2010)

Not trying to hijack here, but do you think the little airbrush compressors would be enough for running a small mist cooler? I would like to have mist capability on my x2 without having to run the big compressor.


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## TarheelTom (Aug 1, 2010)

Looked in Wal~Mart recently and they had three different aquarium pumps. The most expensive was only perhaps $20 or so.

Tom


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## Davo J (Aug 13, 2010)

black85vette  said:
			
		

> Dave; That is real interesting. I have seen a lot of sewer tanks as they are very common around here. But I have never heard of an aerating pump for one.  Are they common where you are?



Sorry for not answering sooner as I usually get notified and didn't this time.
I don't have a tank so I can't comment on whether there used often. I bought this from a neighbor 2 doors down and they told me they closed in the tank and this pump was to aerate it.
It is really quiet, were it is sitting is on the other side of our bedroom wall and runs 24/7.
We hear the bubbles in the tank but not the pump.
Dave


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## Blogwitch (Aug 13, 2010)

Just to answer Websterz question.

I shouldn't think so, they just don't have the volume output. 

On my spraymist it is the volume that counts, not the pressure.


Bogs


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