# Cutting an eheim impeller to reduce flow...



## JustLikeAPill (Oct 9, 2006)

I have an ecco 2236 and am using it on a mini-M. Obviously it is too strong so I turn it down with the valve on the outflow.

The problem is that if I want to service the filter, I have to close the valve all the way and then opening it to get the same amount of flow is tricky, at least for me. It takes time to tweak it and that is time I don't want to spend doing that if I dont have to. 

I would like remove one of the three "fins" if the imepeller to reduce the flow.... i want to reduce it by half. I have also thought of cutting each fin in half to make them shorter. Has anyone done anything like this? This way i could open the outflow valve all the way but have way less flow.

Ane no, downgrading to a smaller filter isnt going to happen since this one is practically new.


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## Left C (Jun 14, 2005)

I wonder if you could use a 2232 or 2234 impeller to get the flow rate that you desire with your 2236??? I know that you can swap the 2215 and 2217 impellers around.


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## cino (May 1, 2011)

I think you already know the answer and that is THE ONLY ANSWER. You can try changing your expensive ADA filter media (and that won't be the answer either) but then you will foul the filter in other ways. You are looking for answers when you already know what is wrong and what must be done. You start using flow valves and other means you are just destroying what you already paid good money for. Any Eheim filter I am familiar with will not tollerate alterations of any kind.


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## cino (May 1, 2011)

PS, Maybe you should ask Eheim!!!!!!!!! I still think the answer is obvious however. You can contact Eheim directly by getting the phone number off of Eheimparts.com (sorry I do not have it readily available) and talk to Earnesto as he usually covers the phones.


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## JustLikeAPill (Oct 9, 2006)

I know what is wrong... It is a filter rated at 180 GPH on a 5.5 gallon tank, But I had the 2236 on my 60-P then downgraded to a mini-m so... Dont want to buy a new filter. I am a college student : ) 

You can throttle down the flow on eheims by using the valve on the outflow (never the inflow) and eheim has told me it is fine and a lot of people do that. It doesnt hurt the filter. However, it is a PITA when it comes to finding the sweet spot every time you service the filter... For me at least.

Using an impeller meant for a smaller ecco model is a good idea and I will ask Eheim if I can do that. Thanks!

I asked about cutting the impeller fins because Tom Barr has done that to make microbubbles when using a canister as a reactor and the filter didnt seem to be bothered. He even attached mesh/foam to an impeller somehow an the filter still worked fine.


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## onefang (Apr 10, 2011)

I too emailed Eheim about using the valves to throttle the filters down. They responded, saying that since the pumps have a magnetically coupled impeller, decreasing flow with valves has no effect on pump life. The pump heads are designed specifically not to be damaged by flow obstructions, because after all, it's a filter and it'll slowly get dirty which reduces flow. 

I'd say, clip some of the impeller blades. Or you could use an extra inline valve(available at your local home depot) on your output to set flow. That way, you'll be able to monkey with your double taps without throwing off your flow setting.


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## Left C (Jun 14, 2005)

onefang said:


> ... Or you could use an extra inline valve(available at your local home depot) on your output to set flow. That way, you'll be able to monkey with your double taps without throwing off your flow setting.


Good idea! This might be the cheapest route.


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## onefang (Apr 10, 2011)

I just found this on HD's website, and it shows that they stock it in store:










Just get the correct sized barbs, and thread them in. Should cost less than $5 with the barbs.


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## cino (May 1, 2011)

Interesting, I stand corrected. I thought that it might have the same effect as a venturi if you tried cutting down output. :banplease


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## onefang (Apr 10, 2011)

It's funny, I was just cleaning my shed and found this:










It's your if you want it. It's got 1/2" barbs. If I remember right, that's what the output on a 2236 uses.


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## JustLikeAPill (Oct 9, 2006)

Perfect! I will PM you!


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## Newt (Apr 1, 2004)

I wouldnt cut the impeller fins because if it becomes unbalanced (as it most likely will) it will wobble and can damage the impeller magnet or jam, etc.


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## TAB (Feb 7, 2009)

if I was going to cut the fins, I'd chuck it up in something like a drill press or lathe. then take some type of powered sanding tool( like a belt sander). While the impeller is spining, I'd very, very slowly move the sander in closer. that way all the fins would be the same lenght and should be realtivly balanced.


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## Justindew (Apr 15, 2011)

TAB said:


> if I was going to cut the fins, I'd chuck it up in something like a drill press or lathe. then take some type of powered sanding tool( like a belt sander). While the impeller is spining, I'd very, very slowly move the sander in closer. that way all the fins would be the same lenght and should be realtivly balanced.


I think this would resolve the unbalanced issue if you were to just cut the impeller blades otherwise


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## OVT (Aug 26, 2010)

For what it's worth, one of the blades on my 2026 broke off a while ago. I had to replace the impeler as it was making ungodly rattling noise.


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## niko (Jan 28, 2004)

Unless you do what Tab suggested you will throw the entire ultra complicated contraption off ballance. And it most likely will not tell you right away it is not doing well. It will run seemingly fine but the magnet will be rubbing badly one one side and eventually something will give up. Plastic fusing from melting is not impossible, I've seen it.

Or you can look at a Fluval and get some true wisdom from the master himself. Master of marketing that is.

They use the same size impeller for 2 of their canisters - 305 and 405. The lower rated 305 has fins that are narrower. Meaning that the length of the fins is the same, each blade is the same thickness, but the width is smaller.


From the side:

_________I__________
IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII
IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII

versus

_________I__________
IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII


How do you cut the blades nicely to make them narrow. I can't answer that if you need to be very precise.

--Nikolay


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## bsmith (Dec 13, 2006)

It might be tough for you to do this accurately to get the desired water movement your looking for but whenever I am looking to reduce water movement (not necessarily flow) I just drill out the holes in my spray bar. This doesn't reduce the flow/filtering capacity of the filter it just reduces the pressure that the water is coming out of the spray bar.


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