"gravity vs pump" flow rates

[Nathan A. Smith]

Hi,

Hopefully this is a simple question -- how does the flow rate between
something flowing just from gravity compare to say a 500 gph pump?
Assuming the same tube size.

The reason I ask is I have a veggie filter that is having water feed to it
from a pump and water is returned to the pond via gravity. All the tubing
is of the same size. The pump is putting in more water than my gravity
line can take out. I am trying to figure out my options to correct this.

Thanks for the help

Nasa

[~ jan JJsPond.us]

>Hopefully this is a simple question -- how does the flow rate between
>something flowing just from gravity compare to say a 500 gph pump?
>Assuming the same tube size.
>
>The reason I ask is I have a veggie filter that is having water feed to it
>from a pump and water is returned to the pond via gravity. All the tubing
>is of the same size. The pump is putting in more water than my gravity
>line can take out. I am trying to figure out my options to correct this.
>Thanks for the help
>Nasa

Replace the out-take tubing with a bigger diameter. Your tubing from the
pump has pressure forcing it thru that size pipe/hose at 500 gph, gravity
fed has no such pressure, so tubing must be bigger to allow for more free
flow. ~ jan


See my ponds and filter design:
http://users.owt.com/jjspond/

~Keep 'em Wet!~
Tri-Cities WA Zone 7a
To e-mail see website

[Phyllis and Jim Hurley]

Hi Nathan,

Is it possible for you to return the water via a waterfall/stream to the
pond? That would get you aeration, beauty and no flow problems.
Alteernately, go for a 3" or 4" pipe. Lots of extra return capacity is a
great boon.

Our returns are combinationa of falls, streams, and 4" pipe where needed.
Visible on our site below.

Good luck.

Jim

"Nathan A. Smith" > wrote in message
...
> Hi,
>
> Hopefully this is a simple question -- how does the flow rate between
> something flowing just from gravity compare to say a 500 gph pump?
> Assuming the same tube size.
>
> The reason I ask is I have a veggie filter that is having water feed to it
> from a pump and water is returned to the pond via gravity. All the tubing
> is of the same size. The pump is putting in more water than my gravity
> line can take out. I am trying to figure out my options to correct this.
>
> Thanks for the help
>
> Nasa

[Nathan A. Smith]

On Sun, 08 Aug 2004 14:04:27 -0400, Hal wrote:

> On Sat, 07 Aug 2004 19:37:37 -0600, "Nathan A. Smith"
> > wrote:
>
>>The reason I ask is I have a veggie filter that is having water feed to it
>>from a pump and water is returned to the pond via gravity. All the tubing
>>is of the same size. The pump is putting in more water than my gravity
>>line can take out. I am trying to figure out my options to correct this.
>
> Best option is increase the gravity flow. I would increase pipe
> size. Adding another 1/2 line only increases the pipe volume or flow
> by 1, but double the pipe size will increase the volume/flow by about
> 4.
>
> Put your pump in a bucket and weight it, and set it on blocks if the
> water is too deep, so the rim of the bucket is above the water line
> and a hole in the side of the bucket is below the water line. When
> the bucket fills turn on the pump and see if it empies the bucket.
> If the water level in the bucket begins to fall increase the hole size
> until you find the right size that allows gravity flow through the
> hole to replenish what the pump is taking out. I would pick the next
> bigger pipe size for a return line. I would also consider installing
> it so I could reach one end of the return line so I could clean it out
> with a garden hose.
> Regards,
> Hal


Thanks for all the help.

After looking closer at my setup, I came to the conclusion that the flow
rate out of the veggie filter was fine. It was the flow in that was too
great. I came to this conclusion based on looking at past post on this
news group. Specifically, water should be in the veggie filter for about
20 minutes before going back into the pond. Thus I reduced the flow going
into the veggie filter. This, of course, lead to the problem of having to
much water leave the veggie filter!

After much trial and error, I discovered my 2nd mistake. I placed the out
going hole to low on the veggie filter box. The more water above the
hole, the faster it will exit the box. (has to do with pressure)

Anyways, thanks for all the input

Nasa