Pipe size etc

[Lewie]

Hi all.
I've posted a picture to give an idea of what I'm doing. Take no notice of the bits of pipe and slabs on the final spillway. (The slabs were an attempt to see if narrowing the spillway would work).
I have spent many months faffing with a pond and stream.
I am almost there!
The problem I have now is the final spillway.
The set up is thus:
Pond = 459 litres.
Pump = Laguna 3500 (Max flow rate 3700 LPH or 810 GPH)
Filter = Laguna 12000
Pipe = 20mm braided hose.

Head = approx. 1m from water surface to top of stream.
There is approx. 2.5m of pipe from pump to filter and 6.5m from filter to stream head.

The pipe goes through a large rock that allows the water to spill about a 30cm drop onto pebbles then there is a second narrow (about 20cm) spillway around 2m 'down stream' that spills about 20cm onto pebbles then another 2m ish run to the final spillway that is around 60cm wide.

I'm happy (ish) with the first and second spill but the final one into the pond is too weak and dribbles under the stone. I want a bit of a curtain effect.

My question is, will increasing the size of the pipe do the job?
I tried a temporary run of 32mm push fit straight from the pump to the stream and it increased flow quite dramatically but of course I had by passed the filter (I've been told the filter takes away up to 35% of pressure?)
I then connected the pump to filter using the original 20mm hose and connected the 32mm push fit to the filter.
This also increased flow but not as much as before.
If I use 32mm pipe all the way will it make much difference, a local aquatic centre says not but then I have read on the web that it will???
Should I move the filter from the bottom of the run to the top?
Is the final spillway too wide?
Etc.
Thanks in advance for any info.

 

[RobAmy]

I think you are okay with the pipe size and pump but it is your design that is the problem (no offense). If you want to maintain a flow then you want to build like a bowl design so the water collects then drops a large amount. Do this at each area in front of your drop. This way it does not matter about the size. Also this is where waterfall foam helps if you are losing water under the stone at the last run off. It will go over instead of under. Hope this makes sense. My stream goes from 22 inches to 6ft wide, so width will not matter just how you design to get there. If you want 2 keep the upper 2 areas as is then just do a bowl/catch basin design in the last area just before the drop and you will get a wide flow

Here is what I mean, see how the water is collecting on the liner before the run off. I have a couple more under the stone which you can not see. This is even with just a hose, not a pump

Here you can see the fall off which has that look I think you want

 

[RobAmy]

I want to add if you are not happy with the speed of the flow then pipe size and pump could be a factor. However sometimes increased speed and volume will be to fast and to loud. I think if you work on the design you will be very happy with your current setup.

 

[Lisak1]

RobandAmy just said exactly what I was going to say. To get the effect you are looking for, you need the water to pool before it cascades over so you have enough water to collect and then essentially be forced over the rocks. You also need to keep the water from going under the rocks with waterfall foam. Remember - water takes the path of least resistance. You also had a good idea about decreasing the size of the stream with your slabs- if you place rocks and foam them correctly, you can increase the force of the flow by pushing the same volume of water through a smaller opening. Also notice how RobandAmy placed rocks in the stream to force the water to flow around - another good trick to increase the water flow - force the water to go where you want it to go and you'll create a much more natural look than a straight drop down a gravel path.

We designed our waterfall by literally mimicking falls that occur naturally - on a much smaller scale of course. We studied photos and videos of waterfalls until we understood what we liked and how it was created. Our waterfall rocks were hand selected to create just the look we wanted to achieve. It was probably the hardest part of the whole design of the pond.

 

[Lisak1]

And again - RobandAmy beat me to it! I was going to add that we chose a pump with a variable speed because we weren't exactly sure how much water we would want flowing over the falls. In our case we didn't want the sheet of water that you are looking for, but more a broken stream of water flowing over the rocks. We are able to turn our falls up or down, depending on the look, feel and sound that we are wanting to create at that moment - pretty cool!

 

[Lewie]

Thanks for the replies.
Rob/Amy, after viewing yours I think I'll just fill it in and have a sand pit!!
I would actually like a bit more flow.
When I attached the 32mm pipe direct to the pump it threw the water an extra 100mm further over the centre fall.
Not too noisy either.
I could put up with a bit less so perhaps I should bite the bullet and try the 32mm flexi from pump to filter and filter to fall and hope the filter doesn't take too much pressure away.
As for the bowl, there is one behind the last rock.
It is about 40mm deep so there is plenty of water gathering.
Perhaps I need to tilt the rock more.
It's a bit more involved than I first thought but I'll just have to keep faffing.
I think I'm going to have to buy a new filter as well.
My father sent me the one I have but on delivery the quartz sleeve and the UV bulb were both smashed and by the time I've replaced them and the sponges I'll be close to a new one in cost.
Do I actually need a UV bulb with such a small pond?
I'm not thinking of getting fish, I just want it for wildlife.
Cheers.

 

[Lewie]

Just an update for anyone that may need the info.
I changed the pipe for the 32mm flexi pipe.
It made a huge difference.
The water spilled a good 60-80mm further on the second fall.
Ideally I would like more on the final fall into the pond but that would mean a second smaller pump adding water after the second fall or a bigger single pump using a T piece and pipe after the second fall.
I'll live with what I've got.