Water circulation

[alan Lloyd]

I am currently building a water feature( sorry no fish!) and I am wondering if any of your members can advise me on water circulation.
I have built a two sleeper high bed.I plan to divide the bed up to have a 6m x1 m section where I plan to have water moving over pebbles.In the centre of this length I am placing a rear feed stainless steel cascade.
The cascade will fill a rill ( about20 m long.).At the end of the rill I am placing a sump with a pump and hose which will run back to the rear of the cascade.
The main problem I have is how to circulate the water over the raised pebble section.I think I will need a second pump to aerate the water but I can't quite figure how to circulate the water round ( I am only thinking of circulation to stop the water going stagnant,would the pump aeration be sufficient to prevent this?)
I can't think of a way of using the pump from the sump at the bottom of the rill to both power the cascade and circulate the water over the raised pebble bed?
Hope this make sense,any suggestions most great fully received.

 

[Meyer Jordan]

Supplemental aeration is not a requirement for Decorative Water Features.
One pump should be sufficient to meet your described needs (if I am reading correctly). Water from the stainless steel cascade should flow over the pebble bed into the rill. Flow rate (GPH) of the pump is, of course, the prime consideration here to achieve the visual dynamics that you seek.
Perhaps a diagram of the proposed feature would help. Could you supply one?

 

[alan Lloyd]

Supplemental aeration is not a requirement for Decorative Water Features.
One pump should be sufficient to meet your described needs (if I am reading correctly). Water from the stainless steel cascade should flow over the pebble bed into the rill. Flow rate (GPH) of the pump is, of course, the prime consideration here to achieve the visual dynamics that you seek.
Perhaps a diagram of the proposed feature would help. Could you supply one?

Thanks for reply.
I will try to post a picture later.The cascade feature sump arrangement is a closed loop,so no circulation would reach the pebble bed which runs at right angles to the cascade.The water from the sump goes straight into the feed connection on the back of the cascade,so no water from this loop comes into contact with the water over the pebble bed.I need to circulate the water on the pebble bed to stop stagnation
hope this is clear,I will try to sketch the set up and post later.

 

[alan Lloyd]

Not a great drawing,but I hope it gives you general idea.Will post picture of cascade set up in a minute

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[alan Lloyd]

Set up of cascade.Note it is a closed system.

 

[Meyer Jordan]

Based on the diagram and photo you will need two (2) pumps.
What is the rating (gph or lph) on the pump feeding the cascade weir?

 

[alan Lloyd]

Based on the diagram and photo you will need two (2) pumps.
What is the rating (gph or lph) on the pump feeding the cascade weir?

Have not picked pump yet,I was thinking of 6000 Lph

 

[Meyer Jordan]

How wide is the cascade weir? You will need a flow of 150 Lph/cm minimum for a decent cascade effect.

 

[alan Lloyd]

How wide is the cascade weir? You will need a flow of 150 Lph/cm minimum for a decent cascade effect.

45 cm wide,about a metre drop (two sleepers high)

 

[Meyer Jordan]

45 cm wide,about a metre drop (two sleepers high)

So then you will need at least a 6750 Lph pump to provide the absolute minimum visual effects of a cascade. The one meter head is insignificant.
I would recommend an 8000 Lph pump. This will also provide a decent flow in the rill.