# Needle wheel Pump Rotors



## hoppycalif (Apr 7, 2005)

Over on Tom Barr's forum Tom is suggesting using one of the new cheap, small needlewheel pumps to generate CO2 mist. You can get one now for about $30-$40. But, one of the posters there tried modifying a standard pump rotor into a quasi-needlewheel type by melting a pattern of small holes in each blade. He had very good luck doing that. So, I dug out a surplus Catalina powerhead, a very small one, and tried melting holes in the rotor blades on that:








My hands aren't very steady now, so I wasn't able to put uniform hole patterns in each blade, but I did get 4-5 holes in each blade. I used a needle, heated in a candle flame. Then I melted a hole in the inlet "box", with the flow slits along the sides, to fit some very small diameter CO2 tubing I have. I stuck that in the hole and reassembled it. When I tried it out in a plastic bin of water it worked fine with gentle blowing in the CO2 line, so it is now in my tank.

It does generate CO2 mist, and isn't noisy doing so. I use a CO2 line from the vent valve at the top of my external reactor as a CO2 source. This gives me a big bubble about every 15 seconds. The tank looks almost as filled with tiny bubbles as when I was injecting CO2 directly into a bigger powerhead inlet.

I may try to steady my hands a bit, and melt more holes in each blade - apparently the more holes the better it chops up the CO2 bubbles.


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## HTN86 (Nov 2, 2007)

Wow I would never thought of this idea. The only problem I see with this method is the balance of flow rate and whipping action of the propeller. The more holes there are on the blades, the slower the flow rate. Let us know how it turn out


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## wrkucera (Jan 6, 2008)

HTN86 said:


> Wow I would never thought of this idea. The only problem I see with this method is the balance of flow rate and whipping action of the propeller. The more holes there are on the blades, the slower the flow rate. Let us know how it turn out


or was this part of the plan to over-powerhead yourself knowing that the flow rate would be altered?


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## hoppycalif (Apr 7, 2005)

The flow you need from a powerhead depends on what you want it to do. In my case, I want some more water circulation, now that my plants are getting bigger, and I wanted to try getting better use from my CO2, which builds up bubbles in the external reactor until a mass of them gets swept out. I also like the effect of CO2 mist, even though I don't like the appearance of a full tank of seltzer water. This seems to be a workable compromise. But, I think more holes in the paddles will do better at making really small bubbles.


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## hoppycalif (Apr 7, 2005)

Today I modified my Maxijet 600 powerhead. I used a small finishing nail, heated with a candle, to melt 3 holes, about 1/16" in diameter in each rotor blade, making sure none would be in line with a hole in an adjacent blade. Then I plugged the end of a short piece of acrylic tubing, that an air line fits snugly on, with high viscosity acrylic cement. Just before the cement blob dried completely I poked a needle hole in the middle of the blob. Next I drilled a hole to fit the O.D. of that piece of acrylic tube in the side of the inlet pipe to the powerhead rotor. I used the same high viscosity cement to glue the tube into the hole, leaving a tiny hole for CO2 to bubble through to get into the inlet flow. This tube I connected to the vent line from my external reactor.

It is now in operation, producing a good CO2 mist from the excess CO2 collecting in the top of the external reactor. The tank water looks almost like seltzer water now. All I need to do is adjust the bubble rate until the drop checker just remains green, and the fish aren't bothered. So far they don't seem to care about the CO2 being on.

This is a very easy modification and an easy way to get CO2 mist with a minimum of equipment in the tank - nothing extra if you use a powerhead for more water circulation anyway. I still get good water flow from the powerhead, so it now does double duty. 

The Catalina powerhead I was trying was making an irritating whoosh sound ever time a bubble went through it. The Maxijet barely makes a noise - much smaller bubbles entering the rotor.


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## taekwondodo (Dec 14, 2005)

all the rage at reefcentral is moving away from needle wheels to mesh impellers (using the mesh material used in filters) to get even smaller bubbles on protein skimmers. Search "mesh mod" on reefcentral.

- Jeff


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## hoppycalif (Apr 7, 2005)

taekwondodo said:


> all the rage at reefcentral is moving away from needle wheels to mesh impellers (using the mesh material used in filters) to get even smaller bubbles on protein skimmers. Search "mesh mod" on reefcentral.
> 
> - Jeff


There is a world of difference in difficulty when you compare making any kind of replacement impeller and simply melting a few holes in the paddles of an existing one. That is why I chose to limit my experimenting with the melted hole type. All I was looking for was an easy, inconspicuous method for getting some CO2 mist from the CO2 bubble at the top of my external reactor. The needle wheel or mesh wheel pump may work a lot better, but the effort, for me, would far exceed the benefit.


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## taekwondodo (Dec 14, 2005)

"but the effort, for me, would far exceed the benefit"

Dude - I thought that was the whole point of DIY 

- Jeff


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## hoppycalif (Apr 7, 2005)

taekwondodo said:


> "but the effort, for me, would far exceed the benefit"
> 
> Dude - I thought that was the whole point of DIY
> 
> - Jeff


Good point!

Actually, I do DIY projects primarily for the fun of doing it, secondarily for the benefit of the end product. In this particular case I needed to do a good cleaning of my tank today, and I wanted to finally do something to get more effective CO2. So, I wasn't willing to wait for an order for a $30 needlewheel pump to arrive. That left me with doing DIY on tiny parts, which are just barely within my present ability. I felt pretty good when I didn't stick a hot needle or nail in my finger, didn't set the impeller afire, didn't break it, and the powerhead worked when I got done. All in all, a successful project!


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## ZooKeeper (Oct 16, 2007)

Why melt when one can use a drill bit of even smaller size that a needle? heck of a lot easier as well. Go to your local hobby store - one that sells r/c stuff and buy a few drill bits and a pin vise. You want small? - snort!, you'd get small! Save a candle as well.

ZK


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## hoppycalif (Apr 7, 2005)

Small isn't necessarily better than large for these holes. It is the material left behind that seems to be the important thing. It is that remaining material that chops up the bubbles. 

Generally I would always rather drill a hole than melt one with a hot needle or nail. But, I have been hearing so often that melting holes is easy and works like a charm. I wanted to try it and see for myself.

One problem I have had when drilling holes in plastics is that the drill bit can catch on the plastic material and either break or, much worse, break the plastic. A hot needle or nail wont do that. So, I have to say, both ways to make holes works, and both have advantages and disadvantages.


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## intermediate_noob (Oct 18, 2007)

I was just surfing around for DIY Venturi pages when I stumbled upon this. Very interesting:

http://www.randystacye.com/diythreadwheel.htm

Just thought I would share.


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