Mesh mod with standard impeller
- Thread starter hipertec
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glaudds
New member
What's the purpose the disk, Sam?
I modded my standard impeller on my sedra 5000 because I didn't want to mess with my NW impeller just in case it didn't work out.
What I did was cut the middle of each fin down to the center of the impeller. This left two prongs with a space between them where the whole fin used to be.
I took two layers of mesh and cut the center out to match the center of the impeller. Then I made a cut thru the mesh to the center. This allowed me to slide the two layers of mesh between the prongs of each fin. Place a couple of zip ties to keep it all together.
I did this this afternoon and so far it seems that the head of foam is fluffier and the bubbles are finer in the tube. Hard to quantify with out an air flow meter. We'll see how this works out.
I modded my standard impeller on my sedra 5000 because I didn't want to mess with my NW impeller just in case it didn't work out.
What I did was cut the middle of each fin down to the center of the impeller. This left two prongs with a space between them where the whole fin used to be.
I took two layers of mesh and cut the center out to match the center of the impeller. Then I made a cut thru the mesh to the center. This allowed me to slide the two layers of mesh between the prongs of each fin. Place a couple of zip ties to keep it all together.
I did this this afternoon and so far it seems that the head of foam is fluffier and the bubbles are finer in the tube. Hard to quantify with out an air flow meter. We'll see how this works out.
Last edited:
glaudds
New member
My rationale for doing this (besides not wanting to chop up my NW) is that by not having the disc, it allowed the mesh in the impeller to chop more bubbles since there is no disc on the backside blocking the water flow.
The other thing I saw is that by zip tying the mesh down onto the disk, it kind of flattens the layers of mesh so it's not so as fluffy. Again, this is all conjecture at this time.
I wish I had a KW meter to quantify things....I thought by having a disc more energy is used to spin since there is more mass. I may be wrong, college physics was a long time ago!
flat broke
New member
Glaudds,
Your physics haven't failed you. More mass at a larger diameter is more work if you are trying to spin the wheel the same speed as a lighter one. But, here's the deal, if the pump cavitates, more than it would with the needlewheel, it may actually draw more watts. We tested this by choking down some pumps last weekend and found that if you load them down with a ball valve, they draw fewer watts. It would stand to reason that if the impeller/magnet/field portion on a mag drive, or armature portion on a brush type motor was allowed to spin faster than it could in a fully loaded 0 head situation via inducing extra cavitation, the motor may indeed pull more watts.
However, unless someone has actually tried your version of the mod in addition to the disk method, then observed the results both in terms of wattage drawn by the pumps and airflow through the venturi, they are really just guessing as to what may or may not be happening behind the volute.
Like yourself, I am hesitant to cut on a brand new needlewheel that has a $50 replacement value, when I can butcher a std impeller for $15 and still probably see appreciable results, not to mention screw up a couple of times before I come up to spending the money I would on a replacement needlewheel. I've just been too busy to go out and grab a new 3500 impeller for my CS-6, but when I do, I plan on leaving all of the blades in place, and using a belt sander to thin them down, I'll then attach the material to the remainder of the blades, and then stack as many layers as I can until negative results are percieved on a killawatt or through bubble production and required outlet height to maintain a certain break line in the neck of the skimmer.
If I get time, I'll bang it out this weekend, but I've still got to finish the doors for my canopy which the wife is starting to get a little impatient about
Chris
Your physics haven't failed you. More mass at a larger diameter is more work if you are trying to spin the wheel the same speed as a lighter one. But, here's the deal, if the pump cavitates, more than it would with the needlewheel, it may actually draw more watts. We tested this by choking down some pumps last weekend and found that if you load them down with a ball valve, they draw fewer watts. It would stand to reason that if the impeller/magnet/field portion on a mag drive, or armature portion on a brush type motor was allowed to spin faster than it could in a fully loaded 0 head situation via inducing extra cavitation, the motor may indeed pull more watts.
However, unless someone has actually tried your version of the mod in addition to the disk method, then observed the results both in terms of wattage drawn by the pumps and airflow through the venturi, they are really just guessing as to what may or may not be happening behind the volute.
Like yourself, I am hesitant to cut on a brand new needlewheel that has a $50 replacement value, when I can butcher a std impeller for $15 and still probably see appreciable results, not to mention screw up a couple of times before I come up to spending the money I would on a replacement needlewheel. I've just been too busy to go out and grab a new 3500 impeller for my CS-6, but when I do, I plan on leaving all of the blades in place, and using a belt sander to thin them down, I'll then attach the material to the remainder of the blades, and then stack as many layers as I can until negative results are percieved on a killawatt or through bubble production and required outlet height to maintain a certain break line in the neck of the skimmer.
If I get time, I'll bang it out this weekend, but I've still got to finish the doors for my canopy which the wife is starting to get a little impatient about
Chris
glaudds
New member
Thanks, Chris...great explanation. I'm not too concerned with power usage as long as the amount of increase isn't that significant.
I'll see if I can get a picture tomorrow...Basically I cut out the middle 3/4 of each blade of the impeller which leaves the two outside edges of the blade. I slipped the mesh between the two edges of the blades and zip tied them into place. Hope that makes sense.
I'll see if I can get a picture tomorrow...Basically I cut out the middle 3/4 of each blade of the impeller which leaves the two outside edges of the blade. I slipped the mesh between the two edges of the blades and zip tied them into place. Hope that makes sense.
flat broke
New member
Actually, everything from the mesh, to the zip ties, to the water in the chamber gets pulled to the outside of the impeller via centrifugal force. Now if you held Glaudds modded impeller in your hand looking down the axis towards the mesh and the top portion was labeled X and the bottom half labeled Y, you can see why the zip ties can't come off. As you start to rotate the impeller/meshwheel, centrifugal force tries to pull the zip ties in region X off the posts, but because the zip ties in region Y are also being pulled to the outside of their respective half, the counter act the effects of centrifugal force on the zip ties in retion X. Hopefully that makes sense.
Glaudds,
Thanks for posting pics. Something to think about... I don't think you need to worry about sandwiching the mesh like you did. Clean work, but the front portion of the old impeller blades is taking up room that could be an extra layer of mesh. An added plus would be that since you don't have to slit the mesh to get it in the groove between the two halves of the blade, you would be less likely to see material expansion due to the mesh separating at your seam.
I hear you on the watts increase issue. It would be small, but the reason it may be important is that it is potentially indicative of more RPM. Since your skimmer runs 24/7, the extra rpm could shorten the overall lifespan of the pump. What would be interesting is to run a Killawatt on a non needlewheel impeller, a needlewheel impeller, and a meshwheel. I'm guesing that the stock NW pulls more watts than the stock impeller, and that certain mesh configurations will pull more watts than the stock NW.
Clean work on the mod. Hopefully I can bang one out this weekend and post some pics of an alternative method.
Chris
glaudds
New member
Thanks Chris...I was concerned about the mesh expansion also with the slit I cut to sandwich the mesh into place. We'll see what happens.
I may eventually cut off the front portion off the impeller and stack another layer of mesh as you are planning to do. I thought I would experiment a little bit before I do something irreversible.
So far the mod has been running about 6 hours and is pulling a higher quantity of wet skimmate than it usually does.
flat broke
New member
Sorry I didn't respond back sooner. We did my brothers during the week. His old NW magnet was toast and the pump had stopped, so no better time than the present.
We went the route I had described above and used 3 layers shaving the factory impeller down to where the blades get slightly longer at the back. We might have been able to squeeze one more layer in, but I knew 3 would work, and getting his skimmer up and running again was first and foremost.
After the impeller was reinstalled, the break line in the neck was higher, and the bubbles went further down into the reaction chamber. After living with the mod for a few days, he says the air noise on the pump is substantially increased, but without a flowmeter, can't verify that it is actually pulling more air. I could tell a difference in the visual appearance of the bubbles in the reaction chamber, and it was more uniform and milky looking.
We've had some family stuff come up, so I've been short on time, but I'll take some before and after pictures when I do the mod on my ER.
Chris
We went the route I had described above and used 3 layers shaving the factory impeller down to where the blades get slightly longer at the back. We might have been able to squeeze one more layer in, but I knew 3 would work, and getting his skimmer up and running again was first and foremost.
After the impeller was reinstalled, the break line in the neck was higher, and the bubbles went further down into the reaction chamber. After living with the mod for a few days, he says the air noise on the pump is substantially increased, but without a flowmeter, can't verify that it is actually pulling more air. I could tell a difference in the visual appearance of the bubbles in the reaction chamber, and it was more uniform and milky looking.
We've had some family stuff come up, so I've been short on time, but I'll take some before and after pictures when I do the mod on my ER.
Chris
glaudds
New member
Thanks for the update, I'm still on the fence whether or not to add another layer of mesh. Just some one week observations from my mod...
There is no distinctive break line in the neck as the bubbles/foam are all uniform all the way up the column. I used to get a distinct stratification of the different bubble sizes..no more.
The skimmer was pulling wet the first couple days and has since settled into a darker product...definitely more than pre-mod.
The skimmer is much more touchier at feeding times and I have to set the delay on the pump longer after feeding to prevent it from overflowing.
All in all, pretty satisfied at this point, noticable difference for such a simple mod.
flat broke
New member
Funny you mention the increased reactivity to feedings/dosing. My brother was telling me the same thing this afternoon. I think I need to find the DIY thread for the airline silencers before I do the mod so I have one on hand if the noise is outta control.
Chris
Chris
glaudds
New member
One month update...still have the same impeller with the two layers of mesh. The skimmer is definitely pulling more skimmate on a consistent basis.
Chaeto growth has slowed downed significantly, and I can only guess it's due to less nutrients in the water.
Here's an obligatory shot of the collection cup, about 3/4" of skimmate in one day. It used to take 3 days to get this amount....
Chaeto growth has slowed downed significantly, and I can only guess it's due to less nutrients in the water.
Here's an obligatory shot of the collection cup, about 3/4" of skimmate in one day. It used to take 3 days to get this amount....
