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[APD] Re: Aquatic-Plants Digest, Vol 11, Issue 8



> Message: 6
> Date: Tue, 6 Jul 2004 11:09:44 -0700 (PDT)
> From: "S. Hieber" <shieber at yahoo_com>
> Subject: Re: [APD] Re: filter vs pump -- or - Siphoning a few more
> details on the ECCO
> To: aquatic plants digest <aquatic-plants at actwin_com>
>
> I confess I haven't read Eheim's instructions for the Eccos
> in a long time. And I mightr be missunderstanding your
> message. Still, I will venture these remarks:
>
> I don't think it matters. If the pump has been running and
> you close the valves, the rotor is still lubricated with
> the water in the filter.

The difficulty in opening the ECCO does not seem to be related to
lubrication but to internal pressure.

>If there is some air in the
> canister, it might settle up around the rotor when the
> water flow is stopped, but for the few minutes between
> closing the valves and unplugging the filter, it shouldn't
> hurt anything. Whether you turn the pump off first or not
> should not matter either.

Because this is a pressure problem, the sequence of closing valves and
turning off the pump matters a lot.

The impeller pushes, with suction on the canister side. So as the IN valve
is closed, what had been low pressure inside the canister becomes even lower
pressure. Then the OUT valve is closed, sealing that slight vacuum in the
unit. Then power off and disconnect the IN and OUT lines at the valves
attached to the tank side of the lines. The canister side has some sort of
auto shut-off that is operated by the handle.

If you do it the "normal way", turning off the power, then closing the
valves, the canister is sealed with a much higher pressure inside, greater
than atmospheric pressure, equal to the head of the water column.
Apparently, a slight vacuum will allow air to enter as the lever is rotated,
while a positive pressure keeps that from happening. This positive pressure
makes the lever hard to move, making the cam slip, leading to forcing it
open with a screwdriver.

>When you shoult off the pump with
> the hoses still open, the water has nowhere to go. Just
> disconnect the hoses after shutting the valves and you
> shouldn't have any problem.

But this is the scenario that gives so much trouble. It is quite
counter-intuitive. It seems that one ought to turn off the pump, then
disconnect the hoses. Closing the valves while the pump is running seems so
very wrong! But that is exactly how the ECCO must be shut down in order to
open easily. If the ECCO is shut down following the instructions, it works
terrifically well! Just like a highly engineered, very expensive,
German-built machine...

> But if the hoses are connected and the valves closed, then
> the canister can't draw in any air or water when you try to
> open it. When you raise the handle back to open the
> canister you are pulling the pump head out of the canister
> and you thereby are trying to cause a vacuum in the
> canister, which tries to pull the pump head back down into
> the canister. It's like trying to pull up the handle on a
> bicycle-tire air pump with the pump's air tube and air
> inlet blocked.

Well, first, if the valves are closed it does not matter whether the hoses
are connected or not. Second, the pump head will come out just fine as long
as there is a vacuum that draws air into the canister as the lever is
rotated.

A vacuum is created when you close the valves in the right sequence, so that
as you operate the lever to roll the cam-locks and open the canister you are
allowing air in, drawn by the vacuum. Doing it the way one would intuitively
do it (pump off, then close valves) leaves a positive pressure in the filter
that the cam lever cannot overcome. I suspect there is a one-way valve
operated by the lever that will not open if there is high pressure inside
the unit relative to atmospheric pressure.

> If you leave the hoses connected and either valve open when
> you remove the pump head, then you risk siphoning water
> from the tank, or at least dumping the water that's in the
> tube, through the open valve, through the pump, and onto
> the floor.

Yes, of course. I'm not admitting to having done that, however.

> If after removing the hoses, you still need something to
> pry the pump head off the canister, then something is wrong
> -- probably the Oring needs a little petroleum jelly and
> nothing more than that.

Although, Eheim does say to lubricate all seals any time you open the unit,
that has nothing to do with this issue.

> For restarting after removing the canister (for cleaning or
> whatever) it helps if the output tube is empty of water or
> at least the end of it above the aquarium water so that air
> doesn't get blocked in the tube.

Yes, the air needs a path to escape.

>But if you return the pump
> head to the canister, reattach the hoses and open the
> valves, you should then be able to work the handle freely,
> which will suck water in through the intake on the
> pull-the-handle-back stroke and (manually) pump it out
> through the output tube on the forward stroke. The
> ball-valve keeps the water from being sucked in through the
> output tube. Once you draw enough water into the siphon
> tube to start the siphon, the canister will fill and you
> can then turn on the pump.

Yes. If the tank is nearly full, with the output line above the water level
and only an inch or two from the water to the rim, the lever will prime with
one pull or less. The Eheim instructions never actually mention that you
want to wait until the tank is nearly full before you try to prime the
units, but it works better that way (the pictures show the set- up with
output line just above water). The priming units can only provide so much
suction, about 4 inches of head seems to be the max, IME.

> The only trouble I've had is with an airlock in the ouput
> tube preventing the canister from filling all the way and
> the rotor not having enough water to generate a flow.

If you have a spraybar low in the tank, that would be an issue. The air in
the line has to get out somehow. Some filters have the power to blow a large
air bubble down through 18 or 24 inches of water, some do not. If there is
air in the output tube, and the tube is underwater so deep that the bubble
cannot escape, then the easiest thing would be to disconnect the hose, open
the valve and shoot some water into a bucket to draw that bubble out -- that
cleans the line of some build up too which is a good thing.

When I clean a canister, after I disconnect the filter I open both the
tank-side valves and drain some water into a bucket to clean the hoses of
some of that build up. That leaves the output line empty, full of air, and
the input line is full of water, no air. When I restart, the output line is
still empty and above water level so all air in the canister has no choice
but to follow the path of least resistance... up the output line.

>Some
> folks like to fill the canister with water at the sink
> before reassembly, and then just connect the tubes and turn
> on the pump. If that works for you, go for it but if
> there's a tad too much air left in the canister, the rotor
> won't be able to pump. If there is a tad too much water, it
> will spill when you put the pump head back on the canister.

Well, that is just wrong -- that may be necessary for a Fluval (my 303 for
example) but should not be necessary for an Eheim. Some folks ought to take
a long look at the instructions and they'd see what they ought to be doing.
Funny thing about Eheim, they use pictures to show how the set-up ought to
be, and those pictures do not say it MUST be that way, but the units are
designed to be set up that way. If you set it up that way and follow the
instructions, it works like the well engineered German-designed machine that
it is.

>
> Anyone wonder why lfss sell beginners backfilters? ;-)

Yeah, they are for folks who won't read instructions. ;-)

Ann Viverette

> --- Ann Viverette <annv777 at houston_rr.com> wrote:
> > Funny thing about that ECCO, you have to close the IN
> > valve, then close the
> > OUT valve BEFORE you unplug the unit. This is very hard
> > to do since it seems
> > so wrong to let the filter run as you have shut off the
> > water going in. But,
> > if you do this, the lever and cam works just fine.
> >
> > I bought a pair of used ECCOs and recieved a small
> > screwdriver along with
> > instructions from the prior owner that if it got stuck to
> > use the
> > screwdriver to force the locks open. It sounded all wrong
> > to me -- this is
> > supposed to be a highly engineered device, it is supposed
> > to WORK. So, I
> > read the instructions.... It is very hard to resist the
> > urge to unplug the
> > unit before closing the valves, I keep the instrucitons
> > propped in front of
> > the ECCO so I have to look at them before I work on the
> > filter.
> >


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