Eheim Classic Cannister rattle

[Peps]

After about 3 years, my Eheim Classic 2217 cannister has become noisy
with a rattling rubbing sort of sound. This was not sudden but
progressed maybe for the last year.

My first move was to replace the impeller shaft (cheapest option). This
helped, but not much. Today I went to the LFS to buy the impeller
assembly, but was talked out of it by a knowledgable sounding LFS guy.
He said the reason for the the rattle is likely to be that the substrate
has become saturated and so that water is not flowing properly.

The instructions do say:

"... You should change 1/3 * 2/3 of the EHFISUBSTRAT every 6-12
months..." - which I haven't done, but I do keep it clean.

Some things that I am struggling with...

- I thought that the substrate worked by building up bacteria on it's
surface. If this is so, then why change the EHFISUBSTRAT at all? A
different LFS guy in a different shop said not to bother.

- If the LFS guy is correct, then I would expect it to rattle less when
it is first cleaned. It doesn't!

So, does the impeller wear, and if so will this make it rattle? Should I
change the EHFISUBSTRAT as recommended, or is this marketing ploy?

Thanks & happy Australia Day.

[Michi Henning]

"Peps" > wrote in message
...
>
> My first move was to replace the impeller shaft (cheapest option). This
> helped, but not much. Today I went to the LFS to buy the impeller
> assembly, but was talked out of it by a knowledgable sounding LFS guy.
> He said the reason for the the rattle is likely to be that the substrate
> has become saturated and so that water is not flowing properly.

Easy way to find out whether he's right: take out the substrate and run
the filter with just water in it. If it still makes the noise, it's obviously
not the substrate...

> - I thought that the substrate worked by building up bacteria on it's
> surface. If this is so, then why change the EHFISUBSTRAT at all? A
> different LFS guy in a different shop said not to bother.

I think the theory is that, over time, as the substrate clogs up with minute
particles, the overall surface area is reduced, so it's less effective. But
I'm also sure that Eheim like to sell lots of (rather expensive) EhfiSubstrat,
so I'd take the recommendation with a grain of salt... I've run my Eheim
with the same substrate for about two years now, and haven't replaced any
of it. (I have a prefilter on the intake in the tank, which keeps the worst of
the crud out of the main filter, so I guess that helps to extend the life time
of the media.) After all this time, the substrate does as good a job as ever.
If the substrate is really worn out (badly clogged), you should see
a reduction in flow rate over time, and I would also expect to see increasing
ammonia and nitrite levels as the bacteria culture gets too small to cope.

> So, does the impeller wear, and if so will this make it rattle?

It hasn't happened to me, so I can't be sure. But I can imagine the impeller
gradually wearing out, and doing so slighly unevenly. (One blade bending
more than the others, for example.) Over time, that would lead to an increasing
imbalance in the impeller, making it wobble as it rotates. So, I can well
imagine that a new impeller would fix the problem.

Cheers,

Michi.

--
Michi Henning Ph: +61 4 1118-2700
ZeroC, Inc. http://www.zeroc.com

[Blue Gourami]

> He said the reason for the the rattle is likely to be that the substrate
> has become saturated and so that water is not flowing properly.
>
> The instructions do say:
>
> "... You should change 1/3 * 2/3 of the EHFISUBSTRAT every 6-12
> months..." - which I haven't done, but I do keep it clean.
>
> - I thought that the substrate worked by building up bacteria on it's
> surface. If this is so, then why change the EHFISUBSTRAT at all? A
> different LFS guy in a different shop said not to bother.

What I was told at the LFS where I bought my Eheim is that over time
the tiny holes in the Ehfi Substrat become clogged with gunk that no
amount of cleaning will remove and there is less surface available for
the bacteria. This is why it is recommended to change some of the Ehfi
Substrat every 6 months or so.

However, I do not see how this clogging would make the filter rattle.
In my experience, I have found that it is usually air trapped in the
filter that makes it noisy.

Blue Gourami

[Peps]

Michi Henning wrote:
> "Peps" > wrote in message
> ...
>
>>My first move was to replace the impeller shaft (cheapest option). This
>>helped, but not much. Today I went to the LFS to buy the impeller
>>assembly, but was talked out of it by a knowledgable sounding LFS guy.
>>He said the reason for the the rattle is likely to be that the substrate
>>has become saturated and so that water is not flowing properly.
>
>
> Easy way to find out whether he's right: take out the substrate and run
> the filter with just water in it. If it still makes the noise, it's obviously
> not the substrate...

That is kind of obvious, and I hadn't thought of it. I have run it empty
recently when cleaning, and it did rattle, so that one is put to bed.
>
>
>>- I thought that the substrate worked by building up bacteria on it's
>>surface. If this is so, then why change the EHFISUBSTRAT at all? A
>>different LFS guy in a different shop said not to bother.
>
>
> I think the theory is that, over time, as the substrate clogs up with minute
> particles, the overall surface area is reduced, so it's less effective. But
> I'm also sure that Eheim like to sell lots of (rather expensive) EhfiSubstrat,
> so I'd take the recommendation with a grain of salt... I've run my Eheim
> with the same substrate for about two years now, and haven't replaced any
> of it. (I have a prefilter on the intake in the tank, which keeps the worst of
> the crud out of the main filter, so I guess that helps to extend the life time
> of the media.) After all this time, the substrate does as good a job as ever.
> If the substrate is really worn out (badly clogged), you should see
> a reduction in flow rate over time, and I would also expect to see increasing
> ammonia and nitrite levels as the bacteria culture gets too small to cope.
>
All readings are good, so I keep on my sceptical hat.
>
>>So, does the impeller wear, and if so will this make it rattle?
>
>
> It hasn't happened to me, so I can't be sure. But I can imagine the impeller
> gradually wearing out, and doing so slighly unevenly. (One blade bending
> more than the others, for example.) Over time, that would lead to an increasing
> imbalance in the impeller, making it wobble as it rotates. So, I can well
> imagine that a new impeller would fix the problem.
>
> Cheers,
>
> Michi.
>
> --
> Michi Henning Ph: +61 4 1118-2700
> ZeroC, Inc. http://www.zeroc.com
>

[Peps]

Blue Gourami wrote:

>>He said the reason for the the rattle is likely to be that the substrate
>>has become saturated and so that water is not flowing properly.
>>
>>The instructions do say:
>>
>>"... You should change 1/3 * 2/3 of the EHFISUBSTRAT every 6-12
>>months..." - which I haven't done, but I do keep it clean.
>>
>>- I thought that the substrate worked by building up bacteria on it's
>>surface. If this is so, then why change the EHFISUBSTRAT at all? A
>>different LFS guy in a different shop said not to bother.
>
>
> What I was told at the LFS where I bought my Eheim is that over time
> the tiny holes in the Ehfi Substrat become clogged with gunk that no
> amount of cleaning will remove and there is less surface available for
> the bacteria. This is why it is recommended to change some of the Ehfi
> Substrat every 6 months or so.
>
> However, I do not see how this clogging would make the filter rattle.
> In my experience, I have found that it is usually air trapped in the
> filter that makes it noisy.

Thanks. I don't think it is air, as it makes a different noise when it
has air in. This is more mechanical. Putting this together with the
previous reply, it sounds like the new impeller is worth the investment.
Worst case is I have a spare.

>
> Blue Gourami