Air-Powered Water Jet/Propeller?

[James Croney]

I see the air-powered fish tank decorations all over the internet. And I have tried to google my idea here, but .... the terms overlap so badly i get an ocean of half-related stuff. Could anyone suggest some search terms for me, or mention a product they may have heard of before?

I would like to find an air-line powered submersible propeller with a fish-safe cage. In my head, the air line that would normally be hooked up to an air stone feeds a small bubble-driven or slight-pressure-driven mechanism that turns a propeller shaft. The purpose would not be to get air into the water so much as increase flow.

As a note, i already have air bubbles with a small gravel filter. So really just want some low-rpm version of a normal tank propeller.

 

Thanks for any thoughts!  Also, any other air-powered thing to suggest. I have an extra line in my airline due to some bad planning and need to fill it. LOL

[Guppysnail]

Look into the coop powerhead. They are not air driven or a decor item however I ended up with 4 I loved themso much. A coop prefilter sponge or regular sponge filter attaches to keep critters safe. They can be positioned anywhere and a zip tie over some sponge can decrease the flow. They literally just plug in and suction cup on. I use them with CPD guppies (fry do fine with it. Panda and Pygmy cory and pleco as well as shrimp and an assortment of snails. The prefilter add extra surface for biological filtration. I love them!😍

If you post a pic of how the extra airline is folks can give suggestions for just “capping it off”

Edited February 17, 2022 by Guppysnail

[Torrey]

On 2/17/2022 at 11:57 AM, James Croney said:

I see the air-powered fish tank decorations all over the internet. And I have tried to google my idea here, but .... the terms overlap so badly i get an ocean of half-related stuff. Could anyone suggest some search terms for me, or mention a product they may have heard of before?

I would like to find an air-line powered submersible propeller with a fish-safe cage. In my head, the air line that would normally be hooked up to an air stone feeds a small bubble-driven or slight-pressure-driven mechanism that turns a propeller shaft. The purpose would not be to get air into the water so much as increase flow.

As a note, i already have air bubbles with a small gravel filter. So really just want some low-rpm version of a normal tank propeller.

 

Thanks for any thoughts!  Also, any other air-powered thing to suggest. I have an extra line in my airline due to some bad planning and need to fill it. LOL

Look at MD Fishtanks, I can't remember which videos... his natural river maybe?

He used something that the visual matches what you are describing. 

I would recommend personally recommend using the Co-op powerhead, and the venturi air can be capped to prevent fish injury if you decide not to use the airline. The sponge filters (except the nano and the small) are the perfect base for the Co-op powerhead.

Zenzo made a video on how to use the sponge filter with the powerhead, if I remember correctly. 

[gardenman]

The engineering would get interesting. In theory, it would be easy to make such a device. You would simply need a circular chamber with a water inlet at the bottom and an adjacent air inlet. Then an air escape hole at the top. An impeller on a shaft that extends beyond the air/water chamber that would trap the air and the rising air would turn the impeller which would then turn the propeller on the far end of the shaft to move the water. Where things get complicated is the force required to turn the propellor through the water (and overcome the various friction points) versus the lift provided by the air. You might only be able to move a very small propellor which would have minimal water movement. Air can move a lot of weight through water (air bags are often used to lift cannons and other heavy items from the seabed) but the math of calculating how big a propellor you could use and other issues (the loss of lift as the impellor/propellor gets spinning) could make this an interesting engineering challenge. 

Air doesn't rise as much as water displaces it, so the rate at which water could fall would be limited to acceleration due to gravity or  32+ ft/sec. at most. If you have a 3D printer it could be fun to play with the concept. None of it would be terribly complicated to make. An old HOB shaft with impeller could be used simplifying that aspect of things. 

If the propellor was too big or the friction too high, the air would just bubble out the bottom water inlet instead of turning the shaft. There would be a maximum speed enforced by Mother Nature as the impellor at some point would move faster than the air rises taking away the lift. You might be able to make one with the water intake at the top instead of the bottom (say one o'clock on the round housing) and then have the air creating negative pressure where the impellor isn't air-driven, but water driven. 

I'm not sure you wouldn't get more overall water movement from something like the burping ceramic hippos that were popular in my youth. Those large bubbles they burp out create a fair amount of movement. It's not a current, but it's movement. A burping hippo type air trap that would move a lot of air in gasps out of a larger airlift tube moving more water at a time. I'm just not sure you'd ever get a significant flow.

If you were to try and make a device that would use air pressure alone (like an impact driver or other air-driven tool,) with the air pressure provided by the pump with the air never encountering the water (an air exhaust tube above the water line) and your air pump could provide enough air, you could get a fairly impressive amount of power. It would take a lot of air though. 

[jasper5150]

On 2/17/2022 at 11:31 AM, Guppysnail said:

Look into the coop powerhead. They are not air driven or a decor item however I ended up with 4 I loved themso much. A coop prefilter sponge or regular sponge filter attaches to keep critters safe. They can be positioned anywhere and a zip tie over some sponge can decrease the flow. They literally just plug in and suction cup on. I use them with CPD guppies (fry do fine with it. Panda and Pygmy cory and pleco as well as shrimp and an assortment of snails. The prefilter add extra surface for biological filtration. I love them!😍

If you post a pic of how the extra airline is folks can give suggestions for just “capping it off

Goofed on that👆!
how much flow does the power head have? I have a sponge filter now. Don’t want to cause a lot of flow and stress my fish. Have corys, barbs and a betta