# Can anyone tell me for certain...?



## scubadiver (Aug 23, 2009)

Can anyone tell me for certain if an impeller for a Rena XP4 canister filter will fit into an XP3?

I just bought (3) XP3's for half of what (3) XP4's would have cost and I could spend $29 to boost them to the flow of the XP4 if the impellers fit.

I read here that the XP1, XP2 and XP3"s interchange. But I also thought someone might have said that the shaft might be longer on the XP4.

Can someone that knows absolutely for sure set me straight?

Thanks


----------



## csnake (Feb 22, 2009)

I've been wondering that for myself... and if they are interchangeable, what is it about the xp4 impellor that boosts the water flow so much?


----------



## Strohs58 (Aug 3, 2009)

Well I hope they interchange, I ordered an xp4 impeller to put in my XP3. If it doesn't work...I'll have a back up impeller for the xp4. Guess I could have opened up each filter and swapped them as a test. Oh well cant think of everything all the time.


----------



## KaiserSousay (Nov 2, 2008)

Strohs58 said:


> Well I hope they interchange, I ordered an xp4 impeller to put in my XP3. If it doesn't work...I'll have a back up impeller for the xp4. Guess I could have opened up each filter and swapped them as a test. Oh well cant think of everything all the time.


I`ll be watching to see if they interchange opcorn:


----------



## cjacob316 (Dec 4, 2008)

has anyone actually bothered to look at all of the specs for the filters? i doubt it'sas simple as using the impeller, did you notice that the watt usage of the xp4 is almost twice that of the xp3, it's not just the size of the impeller that increases the flow, you will not have the output of the xp4 when you do this

has anyone put a flow meter on it to see if it actully increses flow at all? a alrger impeller may slow the motor down, decreasing flow, i have a filter that had a higher flow rate than a different filter with a larger impeller


----------



## Toby_H (Apr 15, 2005)

Dr Foster & Smith lists different product #s for each impeller... as less as lists different "manufacturing #"s for each impeller...

But according to www.planetrena.com they have the same part number... as found here about 4/5 of the way down...
http://rena-aquatics-outlet.planetrena. ... s-All.html


----------



## Strohs58 (Aug 3, 2009)

Well, the XP4 impeller came in the mail today.

Good news is yes they interchange. :thumb:

A visual comparison of the impeller shows 3 blades on the XP4 impeller, compared to 6 blades on the XP3s impeller. I don't know anything about impeller design, maybe someone reading this does and can explain how 3 blades beats 6. :-?

Now the very scientific flow test, measured by the very accurate index finger in front of the output tube. Is there a significant difference in flow rate???

Not so much, and if anything it might actually be less... :?

and in the bone head move of the night, I took pictures of the two impellers side by side, however I deleted them somehow before getting them uploaded.


----------



## Toby_H (Apr 15, 2005)

Strohs58 said:


> I don't know anything about impeller design, maybe someone reading this does and can explain how 3 blades beats 6. :-?


Well, as mentioned the XP4 uses more watts so I think the higher flow rate of the XP4 compared to the XP3 coudl be attributed to a stronger motor...

I don't claim to "understand impeller design", but I'm sure it's a little deeper than "more is better!"



Strohs58 said:


> Now the very scientific flow test, measured by the very accurate index finger in front of the output tube. Is there a significant difference in flow rate???
> 
> Not so much, and if anything it might actually be less... :?


Well... I guess those extra blades did help 



Strohs58 said:


> and in the bone head move of the night, I took pictures of the two impellers side by side, however I deleted them somehow before getting them uploaded.


Sheeesh... and I thought I was the only one who did such things... lol

But if these two are interchangable... and the XP4 impeller appears to move less water than the XP3 impeller when used on the XP3...

This may suggest that the XP3 impeller moves more water than the XP4 impeller...

Therefore one could suspect that using the XP3 impeller on the XP4 might improve water flow through the XP4...

Though of course it's possible that The XP guys did a little testing and this might not be true...

I gues it's also possible, but very unlikely, that Strohs58's finger is out of calibration...

:thumb:


----------



## cjacob316 (Dec 4, 2008)

it makes sense that even if there are less blades, but they are bigger, then it pushes more water if it spins at a higher rate, but the bigger blades actually slows the smaller moter, also, the increased number of blades for the smaller moter is probably more efficiant let's look at airplanes for examples

the p-51 and the corsair both had 4 bladed props, yet the p-51 was a much faster plane for the simple fact of higher rpm's


----------



## cjacob316 (Dec 4, 2008)

helicopters use more blades, yet they spin at lower rpms


----------



## Toby_H (Apr 15, 2005)

cjacob316 said:


> helicopters use more blades, yet they spin at lower rpms


What?! My GI Joe Helicopter had 2 blades and it HAULTED A$$


----------



## cjacob316 (Dec 4, 2008)

yeah for some reason i thought i had seen some with 6 blades... ignore my statement

but it still stands true, p-51's 4blades, very fast, new, stunt/racing planes 2-3 blades, so much faster than p-51's

so i guess that's a better example, a p-51 would lose a lot of speed if it just had a 2blade prop


----------



## KaiserSousay (Nov 2, 2008)

Thanks for posting your results on fit-n-function.
Special :thumb: on your flow test :lol: 
Already stuck it my â€œwhat fits whatâ€


----------



## Strohs58 (Aug 3, 2009)

Toby_H said:


> But if these two are interchangable... and the XP4 impeller appears to move less water than the XP3 impeller when used on the XP3...
> 
> This may suggest that the XP3 impeller moves more water than the XP4 impeller...
> 
> ...


Well it just so happens I have an XP4 on the 150G tank, and as it sits right now I have a spare XP3 impeller. (although I am thinking of putting it back in the XP3)

I could put the XP3 impeller in the XP4 for a test and see where that does to the flow rate.

I'm having trouble though finding a lab that calibrates index fingers. 

Anybody want to test if the impeller of a P51 will fit in an XP4??? :drooling:



KaiserSousay said:


> Thanks for posting your results on fit-n-function.
> Special :thumb: on your flow test :lol:
> Already stuck it my â€œwhat fits whatâ€


----------



## Deeda (Oct 12, 2012)

The tests would be more accurate if you had a flow meter available (or timed how long to fill a gallon container method) and were performed with the filters packed with the same media, hose lengths & on the same tank height.

How about taking some measurements of the length & diameter of the magnet, as well as the the entire length of the the impeller. 
What is the height & length of the blade. 
What is the diameter & length of the impeller shaft? 
What is the diameter & depth of the impeller cavity?
How many watts is listed for the different model XP's you have?

Inquiring minds want to know.


----------



## Strohs58 (Aug 3, 2009)

Deeda said:


> The tests would be more accurate if you had a flow meter available (or timed how long to fill a gallon container method) and were performed with the filters packed with the same media, hose lengths & on the same tank height.
> 
> How about taking some measurements of the length & diameter of the magnet, as well as the the entire length of the the impeller.
> What is the height & length of the blade.
> ...


Just a little bit about me. In High School Science class I was more interested in how hot the Bunson burner could make a quarter, than actually measuring anything... :dancing:

So were kinda at my limit with the experiment unless you want me to find out at what temp the impeller melts...


----------



## Toby_H (Apr 15, 2005)

Strohs58 said:


> I'm having trouble though finding a lab that calibrates index fingers.


This is easyâ€¦ go in the front yardâ€¦ lick your finger and hold it up in the breezeâ€¦

Then check the weather channel to find out how hard the wind was blowingâ€¦



Strohs58 said:


> So were kinda at my limit with the experiment unless you want me to find out at what temp the impeller melts...


If you start melting stuff you better have video!

Being a little more serious...

It would be good information for the forum in general to know if using the XP3 impeller in the XP4 would increase flow...

So if or when convenient, if you did a little comparison that would rock. You could get fancy and use a flow meter, or just hold a pitcher at the same level as the aquarium and time how long it takes to fill it up... and compare each...

Maybe next time you take it apart to clean it anyway...

PS - If you do this test in conjunction with a filter cleaning, keep in mind a clean filter will flow faster, so try to use each impeller on a cleaned, or uncleaned filter...


----------



## scubadiver (Aug 23, 2009)

So, is the consensus that for me to get the extra 100GPM out of a filter, I'll need to spend an extra $100 more than the XP3 to buy the XP4 and not waste the $29 for for an XP4 impeller to put in one of my XP3's?

I guess that's OK as I got the XP3's for $109 each and could buy two of them for the price of (1) XP4. I just wanted to keep from having to use two canisters, and it's always kind of fun to screw with things and cheat the system a little bit as I do with my Hydor Koralia's by using #4 impellers in a #3 unit.

Thanks


----------



## cjacob316 (Dec 4, 2008)

i was gonna say i'd rather buy two xp'3 for the price of one xp4 and have more filtration than one can do


----------



## Strohs58 (Aug 3, 2009)

Well I swapped the XP3 impeller back into the XP3 and I'll have to go with the opinion that the impeller makes little difference in flow rate.

A close inspection of the 2 impellers show that other than the difference in the number of blades, the blades on the XP4 impeller is about 4mm longer.

I got the XP4 for $90 slightly used. So picking it over another XP3 was a no brainer, but I originally got the XP3 because I didn't want to pay the extra money for the XP4.


----------

