filter head

[SkyCatcher]

Hi,

I'm trying to understand what exactly is meant by the head (of water) a
filter wuill work to.

Is it the difference, in height, between the inlet & outlet relative to each
other or is it the actual max height the filter will pump to even if the
actual outlet is lower (i.e. if it has to pump up and over the top of the
aquarium and down the inside).

I hope I've explained myself !!


tia Sky.

[Billy]

"SkyCatcher" > wrote in message
...
| Hi,
|
| I'm trying to understand what exactly is meant by the head (of
water) a
| filter wuill work to.
|
| Is it the difference, in height, between the inlet & outlet
relative to each
| other or is it the actual max height the filter will pump to even
if the
| actual outlet is lower (i.e. if it has to pump up and over the top
of the
| aquarium and down the inside).
|


"Head" means the vertical distance the pump must move the water, from
the water source (in aquaria, this is usually the pump itself) to the
uppermost point in the return line. The more vertical distance, the
lower the total volume will be at the outlet due to resistance of
gravity.

http://www.ext.nodak.edu/extpubs/ageng/irrigate/ae1057w.htm for a
more complicated explanation. See 'static head'.




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[Justin Boucher]

Realistically speaking, once the water comes over the top, the weight of the
water moving in the downward motion will produce a vacuum effect (much like
a siphon) and help pull the water up through the line. This usually isn't
enough to worry about unless your water is returning to the level your pump
is sitting at. It's closer to more like the true head is the verticle
distance from your pump to the water outlet. Personally, I wouldn't waste
the time calculating this and would just choose a pump with a high enough
flow rate at the highest head level you have. It could be a bad situation
if your pump didn't have enough head strength to first push the water over
that highes point even though it could reach the output level. Power cycles
and could cause a real problem if your pump turns back on and can't push the
water over the high point.

Justin

"Billy" > wrote in message
...
>
>
> "SkyCatcher" > wrote in message
> ...
> | Hi,
> |
> | I'm trying to understand what exactly is meant by the head (of
> water) a
> | filter wuill work to.
> |
> | Is it the difference, in height, between the inlet & outlet
> relative to each
> | other or is it the actual max height the filter will pump to even
> if the
> | actual outlet is lower (i.e. if it has to pump up and over the top
> of the
> | aquarium and down the inside).
> |
>
>
> "Head" means the vertical distance the pump must move the water, from
> the water source (in aquaria, this is usually the pump itself) to the
> uppermost point in the return line. The more vertical distance, the
> lower the total volume will be at the outlet due to resistance of
> gravity.
>
> http://www.ext.nodak.edu/extpubs/ageng/irrigate/ae1057w.htm for a
> more complicated explanation. See 'static head'.
>
>
>
>
> ---
> Outgoing mail is certified Virus Free.
> Checked by AVG anti-virus system (http://www.grisoft.com).
> Version: 6.0.771 / Virus Database: 518 - Release Date: 9/28/2004
>
>

[SkyCatcher]

Thanks Billy - but I'm still not totally sure....so here is a pictoral
attempt -

____t
| |
| |
| |
| |
x |
|
|
y


x - filter inlet pipe position in aquaria
y - top of filter outlet
t - the top of the aquaria

the differenct between x & y is 2ft
the difference between y & t is 6ft

so do I need a pump with a head of 6ft (I imagine this is ithe case) or 2ft?

ta Sky.




"Billy" > wrote in message
...
>
>
> "SkyCatcher" > wrote in message
> ...
> | Hi,
> |
> | I'm trying to understand what exactly is meant by the head (of
> water) a
> | filter wuill work to.
> |
> | Is it the difference, in height, between the inlet & outlet
> relative to each
> | other or is it the actual max height the filter will pump to even
> if the
> | actual outlet is lower (i.e. if it has to pump up and over the top
> of the
> | aquarium and down the inside).
> |
>
>
> "Head" means the vertical distance the pump must move the water, from
> the water source (in aquaria, this is usually the pump itself) to the
> uppermost point in the return line. The more vertical distance, the
> lower the total volume will be at the outlet due to resistance of
> gravity.
>
> http://www.ext.nodak.edu/extpubs/ageng/irrigate/ae1057w.htm for a
> more complicated explanation. See 'static head'.
>
>
>
>
> ---
> Outgoing mail is certified Virus Free.
> Checked by AVG anti-virus system (http://www.grisoft.com).
> Version: 6.0.771 / Virus Database: 518 - Release Date: 9/28/2004
>
>

[pausto]

SkyCatcher wrote:
>
> Hi,
>
> I'm trying to understand what exactly is meant by the head (of water) a
> filter wuill work to.
>
> Is it the difference, in height, between the inlet & outlet relative to each
> other or is it the actual max height the filter will pump to even if the
> actual outlet is lower (i.e. if it has to pump up and over the top of the
> aquarium and down the inside).
>
> I hope I've explained myself !!
>
> tia Sky.

Sky,
From info gathered while shopping for pumps, I got this impression;

Measuring a system for the height that needs to be over come, is the
vertical measurement from the surface of the body of water where the
pump gets its water from, to the surface of the water where the pump
pumps the water to. This assumes that the return line is submerged
somewhere below the surface of the tank water (it doesn't matter how
deep).
For a canister filter, receiving and sending its water to the same
body of water (same elevation) the height measurement would be zero.
The loops over the edge don't affect this calculation, nor do the
depth of the line below the water line. I'm guessing this is why
canister filters, and power heads, are sold with single flow rates
listed.
For an open sump type filter, the measurement would be the vertical
distance from the surface of the water in the pump compartment of the
sump, to the surface of the water in the aquarium. Pumps for this
purpose tend to be sold with a chart that indicates how much water
volume will flow at various required heights.
Some of these pumps have a single flow marked on the box. This is
usually the free flow AKA max flow (flow at zero feet).

For a return line that ends above the surface of the tank water,
then the upper measurement would be to the opening of the return line,
not the highest point of the return line. Unless, (unusual but...) if
the diameter of the descending portion of none submerged return line
is so large that air can get back up into it, breaking the descending
syphon, then the upper measurement would be at that point where the
water begins to 'spill' probably at the crest bend.

Of course, none of this accounts for loss from hoses, fittings,
valves, restricted filters and such.

HT(rambling)H
Paul

[NetMax]

"pausto" > wrote in message
...
> SkyCatcher wrote:
> >
> > Hi,
> >
> > I'm trying to understand what exactly is meant by the head (of water)
a
> > filter wuill work to.
> >
> > Is it the difference, in height, between the inlet & outlet relative
to each
> > other or is it the actual max height the filter will pump to even if
the
> > actual outlet is lower (i.e. if it has to pump up and over the top of
the
> > aquarium and down the inside).
> >
> > I hope I've explained myself !!
> >
> > tia Sky.
>
> Sky,
> From info gathered while shopping for pumps, I got this impression;
>
> Measuring a system for the height that needs to be over come, is the
> vertical measurement from the surface of the body of water where the
> pump gets its water from, to the surface of the water where the pump
> pumps the water to. This assumes that the return line is submerged
> somewhere below the surface of the tank water (it doesn't matter how
> deep).
> For a canister filter, receiving and sending its water to the same
> body of water (same elevation) the height measurement would be zero.
> The loops over the edge don't affect this calculation, nor do the
> depth of the line below the water line. I'm guessing this is why
> canister filters, and power heads, are sold with single flow rates
> listed.
> For an open sump type filter, the measurement would be the vertical
> distance from the surface of the water in the pump compartment of the
> sump, to the surface of the water in the aquarium. Pumps for this
> purpose tend to be sold with a chart that indicates how much water
> volume will flow at various required heights.
> Some of these pumps have a single flow marked on the box. This is
> usually the free flow AKA max flow (flow at zero feet).
>
> For a return line that ends above the surface of the tank water,
> then the upper measurement would be to the opening of the return line,
> not the highest point of the return line. Unless, (unusual but...) if
> the diameter of the descending portion of none submerged return line
> is so large that air can get back up into it, breaking the descending
> syphon, then the upper measurement would be at that point where the
> water begins to 'spill' probably at the crest bend.
>
> Of course, none of this accounts for loss from hoses, fittings,
> valves, restricted filters and such.
>
> HT(rambling)H
> Paul

Very nice explanation.
--
www.NetMax.tk

[Billy]

"SkyCatcher" > wrote in message
...
| Thanks Billy - but I'm still not totally sure....so here is a
pictoral
| attempt -
|


Head is the starting point of the water to the highest point the
water has to be pushed. In your case, 6 feet. As pointed out by AP,
there is a slight vacuum effect, but don't worry about that here too
much. Get a pump that has your desired flow rate at six feet of head.


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[pausto]

NetMax wrote:
>
> "pausto" > wrote in message
> ...
> > SkyCatcher wrote:
> > >
> > > Hi,
> > >
> > > I'm trying to understand what exactly is meant by the head (of water)
> a
> > > filter wuill work to.
> > >
> > > Is it the difference, in height, between the inlet & outlet relative
> to each
> > > other or is it the actual max height the filter will pump to even if
> the
> > > actual outlet is lower (i.e. if it has to pump up and over the top of
> the
> > > aquarium and down the inside).
> > >
> > > I hope I've explained myself !!
> > >
> > > tia Sky.
> >
> > Sky,
> > From info gathered while shopping for pumps, I got this impression;
> >
> > Measuring a system for the height that needs to be over come, is the
> > vertical measurement from the surface of the body of water where the
> > pump gets its water from, to the surface of the water where the pump
> > pumps the water to. This assumes that the return line is submerged
> > somewhere below the surface of the tank water (it doesn't matter how
> > deep).
> > For a canister filter, receiving and sending its water to the same
> > body of water (same elevation) the height measurement would be zero.
> > The loops over the edge don't affect this calculation, nor do the
> > depth of the line below the water line. I'm guessing this is why
> > canister filters, and power heads, are sold with single flow rates
> > listed.
> > For an open sump type filter, the measurement would be the vertical
> > distance from the surface of the water in the pump compartment of the
> > sump, to the surface of the water in the aquarium. Pumps for this
> > purpose tend to be sold with a chart that indicates how much water
> > volume will flow at various required heights.
> > Some of these pumps have a single flow marked on the box. This is
> > usually the free flow AKA max flow (flow at zero feet).
> >
> > For a return line that ends above the surface of the tank water,
> > then the upper measurement would be to the opening of the return line,
> > not the highest point of the return line. Unless, (unusual but...) if
> > the diameter of the descending portion of none submerged return line
> > is so large that air can get back up into it, breaking the descending
> > syphon, then the upper measurement would be at that point where the
> > water begins to 'spill' probably at the crest bend.
> >
> > Of course, none of this accounts for loss from hoses, fittings,
> > valves, restricted filters and such.
> >
> > HT(rambling)H
> > Paul
>
> Very nice explanation.
> --
> www.NetMax.tk

Thanks for the response NetMax. I was hoping I had absorbed the info
somewhat correctly. There's a ton of, sometimes confusing, info to
weed through when selecting pumps and plumbing.

Paul

[NetMax]

Regarding the canister, yes - in theory. The weight of the water in the
intake hose = the weight in the return hose, and if both hose ends are
underwater or close to the water surface, then there is very little
'head' for the pump to work against.

In practise, this weight has to exert itself somewhere, and it will be on
the gasket seals of the hose connectors and canister body. If you put
the canister too far below the tank, seals may fail.

Hose length also affects performance, simply because of the weight of the
water to get started and the rolling resistance (through elbows etc), but
in normal applications, it's not significant enough to worry about.

Some people put a pinhole in the intake hose to cause the flow to break
in the event of a canister seal failure causing your tank to start
emptying itself on to your floor, ymmv.
--
www.NetMax.tk

"SkyCatcher" > wrote in message
...
> Great explaination....
>
> so if I'm using an external canister filter as you describe, it doesn't
> matter how low down below a tall aquarium I have the filter as the net
> resultant head is zero (allowing of course for frictional losss in long
run
> of pipe) - correct?
>
> (almost) a happy man!, Sky.
>
>
> "pausto" > wrote in message
> ...
> > SkyCatcher wrote:
> > >
> > > Hi,
> > >
> > > I'm trying to understand what exactly is meant by the head (of
water) a
> > > filter wuill work to.
> > >
> > > Is it the difference, in height, between the inlet & outlet
relative to
> each
> > > other or is it the actual max height the filter will pump to even
if the
> > > actual outlet is lower (i.e. if it has to pump up and over the top
of
> the
> > > aquarium and down the inside).
> > >
> > > I hope I've explained myself !!
> > >
> > > tia Sky.
> >
> > Sky,
> > From info gathered while shopping for pumps, I got this impression;
> >
> > Measuring a system for the height that needs to be over come, is
the
> > vertical measurement from the surface of the body of water where the
> > pump gets its water from, to the surface of the water where the pump
> > pumps the water to. This assumes that the return line is submerged
> > somewhere below the surface of the tank water (it doesn't matter how
> > deep).
> > For a canister filter, receiving and sending its water to the same
> > body of water (same elevation) the height measurement would be zero.
> > The loops over the edge don't affect this calculation, nor do the
> > depth of the line below the water line. I'm guessing this is why
> > canister filters, and power heads, are sold with single flow rates
> > listed.
> > For an open sump type filter, the measurement would be the vertical
> > distance from the surface of the water in the pump compartment of the
> > sump, to the surface of the water in the aquarium. Pumps for this
> > purpose tend to be sold with a chart that indicates how much water
> > volume will flow at various required heights.
> > Some of these pumps have a single flow marked on the box. This is
> > usually the free flow AKA max flow (flow at zero feet).
> >
> > For a return line that ends above the surface of the tank water,
> > then the upper measurement would be to the opening of the return
line,
> > not the highest point of the return line. Unless, (unusual but...) if
> > the diameter of the descending portion of none submerged return line
> > is so large that air can get back up into it, breaking the descending
> > syphon, then the upper measurement would be at that point where the
> > water begins to 'spill' probably at the crest bend.
> >
> > Of course, none of this accounts for loss from hoses, fittings,
> > valves, restricted filters and such.
> >
> > HT(rambling)H
> > Paul
>
>

[SkyCatcher]

Great explaination....

so if I'm using an external canister filter as you describe, it doesn't
matter how low down below a tall aquarium I have the filter as the net
resultant head is zero (allowing of course for frictional losss in long run
of pipe) - correct?

(almost) a happy man!, Sky.


"pausto" > wrote in message
...
> SkyCatcher wrote:
> >
> > Hi,
> >
> > I'm trying to understand what exactly is meant by the head (of water) a
> > filter wuill work to.
> >
> > Is it the difference, in height, between the inlet & outlet relative to
each
> > other or is it the actual max height the filter will pump to even if the
> > actual outlet is lower (i.e. if it has to pump up and over the top of
the
> > aquarium and down the inside).
> >
> > I hope I've explained myself !!
> >
> > tia Sky.
>
> Sky,
> From info gathered while shopping for pumps, I got this impression;
>
> Measuring a system for the height that needs to be over come, is the
> vertical measurement from the surface of the body of water where the
> pump gets its water from, to the surface of the water where the pump
> pumps the water to. This assumes that the return line is submerged
> somewhere below the surface of the tank water (it doesn't matter how
> deep).
> For a canister filter, receiving and sending its water to the same
> body of water (same elevation) the height measurement would be zero.
> The loops over the edge don't affect this calculation, nor do the
> depth of the line below the water line. I'm guessing this is why
> canister filters, and power heads, are sold with single flow rates
> listed.
> For an open sump type filter, the measurement would be the vertical
> distance from the surface of the water in the pump compartment of the
> sump, to the surface of the water in the aquarium. Pumps for this
> purpose tend to be sold with a chart that indicates how much water
> volume will flow at various required heights.
> Some of these pumps have a single flow marked on the box. This is
> usually the free flow AKA max flow (flow at zero feet).
>
> For a return line that ends above the surface of the tank water,
> then the upper measurement would be to the opening of the return line,
> not the highest point of the return line. Unless, (unusual but...) if
> the diameter of the descending portion of none submerged return line
> is so large that air can get back up into it, breaking the descending
> syphon, then the upper measurement would be at that point where the
> water begins to 'spill' probably at the crest bend.
>
> Of course, none of this accounts for loss from hoses, fittings,
> valves, restricted filters and such.
>
> HT(rambling)H
> Paul

[Billy]

"SkyCatcher" > wrote in message
...
| Great explaination....
|
| so if I'm using an external canister filter as you describe, it
doesn't
| matter how low down below a tall aquarium I have the filter as the
net
| resultant head is zero (allowing of course for frictional losss in
long run
| of pipe) - correct?
|


Canisters have the benifift of a siphon being created, helping to
push the water back out.


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
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[pausto]

SkyCatcher wrote:
>
> Great explaination....
>
> so if I'm using an external canister filter as you describe, it doesn't
> matter how low down below a tall aquarium I have the filter as the net
> resultant head is zero (allowing of course for frictional losss in long run
> of pipe) - correct?
>
> (almost) a happy man!, Sky.
>

Correct! for flow (allowing for friction loss...).

However, (And I don't think this is going to be a problem for your
setup) this should be said for someone who is thinking of moving their
canister to the basement and pumping to the 2nd floor.

Note: I'm no expert. This is from memory of stuff I read while
shopping for aquarium pumps and plumbing.

As the elevation difference becomes more extreme, the force of the
Static Fill Pressure on the canister seals needs to be considered.
With the canister and lines fully filled/primed, and the pump
turned off; There is approximately 0.43 psi pressure for each foot of
elevation (measured vertically from the canister seal to the tank
water level) that is exerted on the canister seal. It doesn't matter
what the plumbing diameter is, tank size or how many lines run from
the canister. In an open system (which an aquarium is), the Static
Fill Pressure is determined by 'elevation' of the water ).

Elevation difference from the seal to the top of the system
three feet = 1.3 psi
six feet = 2.6 psi
twenty feet = 8.6 psi Ouch! (are my numbers right? Anybody?)

The pressure on the seal will change with the pump running but, I
think, only slightly (negligibly?).

Though I haven't read anything that suggests a typical canister
can't be used on even the tallest aquarium that would fit in a room
with an 8ft ceiling, the shear numbers of newsgroup postings about
leaking canisters would encourage me to keep an extra set of seals on
hand. If your luck runs like mine, and you do keep an extra set on
hand, you'll probably never need them.

Best of luck with your setup,
Paul

--
FULL-ON Clown Loach antics were observed during the writing of this
posting.

[SkyCatcher]

Is it possible then to position the cannister above the inlet hose but below
the outlet - so no siphon ?

This pin hole - does it not leak?


"NetMax" > wrote in message
...
> Regarding the canister, yes - in theory. The weight of the water in the
> intake hose = the weight in the return hose, and if both hose ends are
> underwater or close to the water surface, then there is very little
> 'head' for the pump to work against.
>
> In practise, this weight has to exert itself somewhere, and it will be on
> the gasket seals of the hose connectors and canister body. If you put
> the canister too far below the tank, seals may fail.
>
> Hose length also affects performance, simply because of the weight of the
> water to get started and the rolling resistance (through elbows etc), but
> in normal applications, it's not significant enough to worry about.
>
> Some people put a pinhole in the intake hose to cause the flow to break
> in the event of a canister seal failure causing your tank to start
> emptying itself on to your floor, ymmv.
> --
> www.NetMax.tk
>
> "SkyCatcher" > wrote in message
> ...
> > Great explaination....
> >
> > so if I'm using an external canister filter as you describe, it doesn't
> > matter how low down below a tall aquarium I have the filter as the net
> > resultant head is zero (allowing of course for frictional losss in long
> run
> > of pipe) - correct?
> >
> > (almost) a happy man!, Sky.
> >
> >
> > "pausto" > wrote in message
> > ...
> > > SkyCatcher wrote:
> > > >
> > > > Hi,
> > > >
> > > > I'm trying to understand what exactly is meant by the head (of
> water) a
> > > > filter wuill work to.
> > > >
> > > > Is it the difference, in height, between the inlet & outlet
> relative to
> > each
> > > > other or is it the actual max height the filter will pump to even
> if the
> > > > actual outlet is lower (i.e. if it has to pump up and over the top
> of
> > the
> > > > aquarium and down the inside).
> > > >
> > > > I hope I've explained myself !!
> > > >
> > > > tia Sky.
> > >
> > > Sky,
> > > From info gathered while shopping for pumps, I got this impression;
> > >
> > > Measuring a system for the height that needs to be over come, is
> the
> > > vertical measurement from the surface of the body of water where the
> > > pump gets its water from, to the surface of the water where the pump
> > > pumps the water to. This assumes that the return line is submerged
> > > somewhere below the surface of the tank water (it doesn't matter how
> > > deep).
> > > For a canister filter, receiving and sending its water to the same
> > > body of water (same elevation) the height measurement would be zero.
> > > The loops over the edge don't affect this calculation, nor do the
> > > depth of the line below the water line. I'm guessing this is why
> > > canister filters, and power heads, are sold with single flow rates
> > > listed.
> > > For an open sump type filter, the measurement would be the vertical
> > > distance from the surface of the water in the pump compartment of the
> > > sump, to the surface of the water in the aquarium. Pumps for this
> > > purpose tend to be sold with a chart that indicates how much water
> > > volume will flow at various required heights.
> > > Some of these pumps have a single flow marked on the box. This is
> > > usually the free flow AKA max flow (flow at zero feet).
> > >
> > > For a return line that ends above the surface of the tank water,
> > > then the upper measurement would be to the opening of the return
> line,
> > > not the highest point of the return line. Unless, (unusual but...) if
> > > the diameter of the descending portion of none submerged return line
> > > is so large that air can get back up into it, breaking the descending
> > > syphon, then the upper measurement would be at that point where the
> > > water begins to 'spill' probably at the crest bend.
> > >
> > > Of course, none of this accounts for loss from hoses, fittings,
> > > valves, restricted filters and such.
> > >
> > > HT(rambling)H
> > > Paul
> >
> >
>
>

[Billy]

"SkyCatcher" > wrote in message
...
| Is it possible then to position the cannister above the inlet hose
but below
| the outlet - so no siphon ?
|
| This pin hole - does it not leak?
|
|

Of course, it's a hole. <g> The pin hole should be in a place where
the water squiting out of it will go into the tank. Typically just
above the water line.


---
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[NetMax]

The canister's location should always be below the water line, and then
once the siphon is started, it will drain the contents of the tank until
the water reaches the intake strainer or the leak at the canister
(whichever is higher). In over 30 years with canister filters, I've
never drained a tank in this method. They typically 'weep' leak first if
there is a problem, so I do sometimes keep my canisters in plastic tubs.
However, it always a good idea to check your hose clamps as part of an
annual ritual.

I did manage to drain a tank at work this way though, but at work we were
moving filters around quite often, so it's more of an occupational
hazard. It was only an 250g tank ;~) *it's good thing the floors are
concrete with drains*. It was this one
http://www.2cah.com/netmax/diy_projects/KoiPond/KoiPond.shtml

Regarding the hole drilled into the intake, no it does not leak. My
understanding is that the water flow creates a slight low pressure, and
with a very small hole, it neither leaks water out or sucks air in. I've
never done this myself, but I've heard it described in credible posts.
--
www.NetMax.tk

"SkyCatcher" > wrote in message
...
> Is it possible then to position the cannister above the inlet hose but
below
> the outlet - so no siphon ?
>
> This pin hole - does it not leak?
>
>
> "NetMax" > wrote in message
> ...
> > Regarding the canister, yes - in theory. The weight of the water in
the
> > intake hose = the weight in the return hose, and if both hose ends
are
> > underwater or close to the water surface, then there is very little
> > 'head' for the pump to work against.
> >
> > In practise, this weight has to exert itself somewhere, and it will
be on
> > the gasket seals of the hose connectors and canister body. If you
put
> > the canister too far below the tank, seals may fail.
> >
> > Hose length also affects performance, simply because of the weight of
the
> > water to get started and the rolling resistance (through elbows etc),
but
> > in normal applications, it's not significant enough to worry about.
> >
> > Some people put a pinhole in the intake hose to cause the flow to
break
> > in the event of a canister seal failure causing your tank to start
> > emptying itself on to your floor, ymmv.
> > --
> > www.NetMax.tk
> >
> > "SkyCatcher" > wrote in message
> > ...
> > > Great explaination....
> > >
> > > so if I'm using an external canister filter as you describe, it
doesn't
> > > matter how low down below a tall aquarium I have the filter as the
net
> > > resultant head is zero (allowing of course for frictional losss in
long
> > run
> > > of pipe) - correct?
> > >
> > > (almost) a happy man!, Sky.
> > >
> > >
> > > "pausto" > wrote in message
> > > ...
> > > > SkyCatcher wrote:
> > > > >
> > > > > Hi,
> > > > >
> > > > > I'm trying to understand what exactly is meant by the head (of
> > water) a
> > > > > filter wuill work to.
> > > > >
> > > > > Is it the difference, in height, between the inlet & outlet
> > relative to
> > > each
> > > > > other or is it the actual max height the filter will pump to
even
> > if the
> > > > > actual outlet is lower (i.e. if it has to pump up and over the
top
> > of
> > > the
> > > > > aquarium and down the inside).
> > > > >
> > > > > I hope I've explained myself !!
> > > > >
> > > > > tia Sky.
> > > >
> > > > Sky,
> > > > From info gathered while shopping for pumps, I got this
impression;
> > > >
> > > > Measuring a system for the height that needs to be over come,
is
> > the
> > > > vertical measurement from the surface of the body of water where
the
> > > > pump gets its water from, to the surface of the water where the
pump
> > > > pumps the water to. This assumes that the return line is
submerged
> > > > somewhere below the surface of the tank water (it doesn't matter
how
> > > > deep).
> > > > For a canister filter, receiving and sending its water to the
same
> > > > body of water (same elevation) the height measurement would be
zero.
> > > > The loops over the edge don't affect this calculation, nor do the
> > > > depth of the line below the water line. I'm guessing this is why
> > > > canister filters, and power heads, are sold with single flow
rates
> > > > listed.
> > > > For an open sump type filter, the measurement would be the
vertical
> > > > distance from the surface of the water in the pump compartment of
the
> > > > sump, to the surface of the water in the aquarium. Pumps for this
> > > > purpose tend to be sold with a chart that indicates how much
water
> > > > volume will flow at various required heights.
> > > > Some of these pumps have a single flow marked on the box. This
is
> > > > usually the free flow AKA max flow (flow at zero feet).
> > > >
> > > > For a return line that ends above the surface of the tank
water,
> > > > then the upper measurement would be to the opening of the return
> > line,
> > > > not the highest point of the return line. Unless, (unusual
but...) if
> > > > the diameter of the descending portion of none submerged return
line
> > > > is so large that air can get back up into it, breaking the
descending
> > > > syphon, then the upper measurement would be at that point where
the
> > > > water begins to 'spill' probably at the crest bend.
> > > >
> > > > Of course, none of this accounts for loss from hoses, fittings,
> > > > valves, restricted filters and such.
> > > >
> > > > HT(rambling)H
> > > > Paul

top-posted by replies...

[SkyCatcher]

Many thanks NetMax...


"NetMax" > wrote in message
.. .
> The canister's location should always be below the water line, and then
> once the siphon is started, it will drain the contents of the tank until
> the water reaches the intake strainer or the leak at the canister
> (whichever is higher). In over 30 years with canister filters, I've
> never drained a tank in this method. They typically 'weep' leak first if
> there is a problem, so I do sometimes keep my canisters in plastic tubs.
> However, it always a good idea to check your hose clamps as part of an
> annual ritual.
>
> I did manage to drain a tank at work this way though, but at work we were
> moving filters around quite often, so it's more of an occupational
> hazard. It was only an 250g tank ;~) *it's good thing the floors are
> concrete with drains*. It was this one
> http://www.2cah.com/netmax/diy_projects/KoiPond/KoiPond.shtml
>
> Regarding the hole drilled into the intake, no it does not leak. My
> understanding is that the water flow creates a slight low pressure, and
> with a very small hole, it neither leaks water out or sucks air in. I've
> never done this myself, but I've heard it described in credible posts.
> --
> www.NetMax.tk
>
> "SkyCatcher" > wrote in message
> ...
> > Is it possible then to position the cannister above the inlet hose but
> below
> > the outlet - so no siphon ?
> >
> > This pin hole - does it not leak?
> >
> >
> > "NetMax" > wrote in message
> > ...
> > > Regarding the canister, yes - in theory. The weight of the water in
> the
> > > intake hose = the weight in the return hose, and if both hose ends
> are
> > > underwater or close to the water surface, then there is very little
> > > 'head' for the pump to work against.
> > >
> > > In practise, this weight has to exert itself somewhere, and it will
> be on
> > > the gasket seals of the hose connectors and canister body. If you
> put
> > > the canister too far below the tank, seals may fail.
> > >
> > > Hose length also affects performance, simply because of the weight of
> the
> > > water to get started and the rolling resistance (through elbows etc),
> but
> > > in normal applications, it's not significant enough to worry about.
> > >
> > > Some people put a pinhole in the intake hose to cause the flow to
> break
> > > in the event of a canister seal failure causing your tank to start
> > > emptying itself on to your floor, ymmv.
> > > --
> > > www.NetMax.tk
> > >
> > > "SkyCatcher" > wrote in message
> > > ...
> > > > Great explaination....
> > > >
> > > > so if I'm using an external canister filter as you describe, it
> doesn't
> > > > matter how low down below a tall aquarium I have the filter as the
> net
> > > > resultant head is zero (allowing of course for frictional losss in
> long
> > > run
> > > > of pipe) - correct?
> > > >
> > > > (almost) a happy man!, Sky.
> > > >
> > > >
> > > > "pausto" > wrote in message
> > > > ...
> > > > > SkyCatcher wrote:
> > > > > >
> > > > > > Hi,
> > > > > >
> > > > > > I'm trying to understand what exactly is meant by the head (of
> > > water) a
> > > > > > filter wuill work to.
> > > > > >
> > > > > > Is it the difference, in height, between the inlet & outlet
> > > relative to
> > > > each
> > > > > > other or is it the actual max height the filter will pump to
> even
> > > if the
> > > > > > actual outlet is lower (i.e. if it has to pump up and over the
> top
> > > of
> > > > the
> > > > > > aquarium and down the inside).
> > > > > >
> > > > > > I hope I've explained myself !!
> > > > > >
> > > > > > tia Sky.
> > > > >
> > > > > Sky,
> > > > > From info gathered while shopping for pumps, I got this
> impression;
> > > > >
> > > > > Measuring a system for the height that needs to be over come,
> is
> > > the
> > > > > vertical measurement from the surface of the body of water where
> the
> > > > > pump gets its water from, to the surface of the water where the
> pump
> > > > > pumps the water to. This assumes that the return line is
> submerged
> > > > > somewhere below the surface of the tank water (it doesn't matter
> how
> > > > > deep).
> > > > > For a canister filter, receiving and sending its water to the
> same
> > > > > body of water (same elevation) the height measurement would be
> zero.
> > > > > The loops over the edge don't affect this calculation, nor do the
> > > > > depth of the line below the water line. I'm guessing this is why
> > > > > canister filters, and power heads, are sold with single flow
> rates
> > > > > listed.
> > > > > For an open sump type filter, the measurement would be the
> vertical
> > > > > distance from the surface of the water in the pump compartment of
> the
> > > > > sump, to the surface of the water in the aquarium. Pumps for this
> > > > > purpose tend to be sold with a chart that indicates how much
> water
> > > > > volume will flow at various required heights.
> > > > > Some of these pumps have a single flow marked on the box. This
> is
> > > > > usually the free flow AKA max flow (flow at zero feet).
> > > > >
> > > > > For a return line that ends above the surface of the tank
> water,
> > > > > then the upper measurement would be to the opening of the return
> > > line,
> > > > > not the highest point of the return line. Unless, (unusual
> but...) if
> > > > > the diameter of the descending portion of none submerged return
> line
> > > > > is so large that air can get back up into it, breaking the
> descending
> > > > > syphon, then the upper measurement would be at that point where
> the
> > > > > water begins to 'spill' probably at the crest bend.
> > > > >
> > > > > Of course, none of this accounts for loss from hoses, fittings,
> > > > > valves, restricted filters and such.
> > > > >
> > > > > HT(rambling)H
> > > > > Paul
>
> top-posted by replies...
>
>