Hi guys,
My koi pond and my filter are on different levels - difference is about
70 cm.
I am looking for a solution to regulate the water stream from the pond
to the filter in such a way that the water throughput , regulated by a
valve/shutter, is depending on the water level in the filter. I have
been looking for an electrical valve but most of these valves need more
pressure than 70cm of water can generate; and the low-pressure
operating valves are expensive.
Has anybody already solved such a construction, possibly made a
mechanical valve himself?

I see a possibility to work with an overflow threshold in the upper
part of the pond - but this means that I am only getting surface water
in the filter and that I am very depending on the waterlevel in the
pond ( evaporation in summer!).
I could make a hole in the pond near the level of the filter but if the
filter pump fails my pond will loose all its water, and the calibration
of the right flow of water through this canal seems not
straightforward.
You see I do not have a reliable solution yet, is there anybody with
good suggestions?


H~~level pond~~H---terrace-----H
H ~~~~~~~~~~ H
H H
~~ ======= Valve to be H
. H placed
. H

H """'''lawn'""H~Lvl filter~ H
H H ~~~~~~~~~ H
H H H

How about extra tank between pond and filter with ball cock valve installed,
water in filter drops ball valve opens, water rises ball valve closes, have
the tank and filter at same level and connected below water surface.
Also run submersible pump to first tank, through the ball valve, this will
ensure sufficient flow even if water level drops in pond. you can fit two
port valve so that some water is pumped back into pond as bypass.


"Etienne" wrote in message
ups.com...
Hi guys,
My koi pond and my filter are on different levels - difference is about
70 cm.
I am looking for a solution to regulate the water stream from the pond
to the filter in such a way that the water throughput , regulated by a
valve/shutter, is depending on the water level in the filter. I have
been looking for an electrical valve but most of these valves need more
pressure than 70cm of water can generate; and the low-pressure
operating valves are expensive.
Has anybody already solved such a construction, possibly made a
mechanical valve himself?

I see a possibility to work with an overflow threshold in the upper
part of the pond - but this means that I am only getting surface water
in the filter and that I am very depending on the waterlevel in the
pond ( evaporation in summer!).
I could make a hole in the pond near the level of the filter but if the
filter pump fails my pond will loose all its water, and the calibration
of the right flow of water through this canal seems not
straightforward.
You see I do not have a reliable solution yet, is there anybody with
good suggestions?


H~~level pond~~H---terrace-----H
H ~~~~~~~~~~ H
H H
~~ ======= Valve to be H
. H placed
. H

H """'''lawn'""H~Lvl filter~ H
H H ~~~~~~~~~ H
H H H

I assume the top of your filter is below the level of the surface of your pond, if that is the case my first suggestion would be, raise the filter. If your filter is above the pond then I have misunderstood your post

If I have not misunderstood your post you can, as you suggest, draw only from the surface, ie over a wier, but that has the drawback you mention, ie it is sensitive to water loss.

An alternative would be to have a bottom drain in the pond with no lid and add a stand pipe to that, the top of the stand pipe being the wier. However, around the stand pipe place a bigger bore pipe with a castellated bottom, if the outer pipe rises above the water level in the pond then the annulus between the two pipes draws from the bottom of the pond, if you adjust the length of the outer pipe you could tune it so you get both surface and bottom draw.

A third option could be achieved by having the weir at the down stream end of your plumbing, ie discharge from a stand pipe etc above the filter, that would facilitate drawing the water from any level in the pond. BUT this idea is very sensitive to pipeloss and you would need to keep pipe loss to an absolute minimum. Pipeloss dictates how much the pond's surface has to be above the weir to push the flowrate through the plumbing, I may have this set up at some point in the future when and if I add a pond that is connected to my goldfish pond. The plumbing already largely exists for this and is 110mm sewer pipe for a 1600UK gph flow rate. My thinking is I will have the plumbing discharge into a shallow tank with a large perimeter, the flow over the perimeter/edge of the tank, wier, will be shallow because of the length of the perimeter and will therefore limit the volume of water that would draindown when the pump is switched off. The water going over the edge of the tank will be directed to a waterfall dropping into the lower pond.

However I still suggest raising the filter is your best solution.