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Thread: New Pond
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04-11-2024, 10:38 AM #1
New Pond
Hi all, I'm about to start building a new pond and although I've got a tons of useful information looking through the Pond Diaries, it seems the more I learn, the more I understand how much I don't know.
I've attached a sketch of the layout - the width is 1,700mm all round, and I was planning to have 300mm shoulders along each side (for water plant pots), leaving a 1,100mm wide central section. There are no freezing winters at the site, so I was thinking of making the main pond 600mm deep - would that be practical or absolutely too shallow?
Assuming it'll be 600mm deep, the total volume will be 20,000 litres. As the filter has to be located below water level (the red arrow in the sketch) I assume I will need to use a pressurised system, so I have bought the following:
- PondXpert VariFlow 20,000 pump
- All Pond Solutions PFL 20,000 filter system
- Oase SwimSkim 50 skimmer (which I was planning to tie under the bridge)
- 2 x Bottom Drain 110mm Solvent Weld (Yamitsu)
- and a 600mm wide stainless steel spillway for the waterfall
Are there any essential items missing from my list?
Do I really need the two bottom drains, and if so, should I join them both with 4" pipe via a Y-connector to the pump? I'm not sure if this would cause the smaller lower tank to empty too quickly, and if so, would I need some kind of adjustable flow restrictor somewhere?
I hope I'm not leaving myself open to a barrage of criticism due to newbie errors, but is this plan at least theoretically workable, and what are the other main considerations I need to tackle before and during construction?
Please be gentle and thanks in advance for any comments or suggestions that might prevent me from doing something stupid.
Cheers!
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04-11-2024, 12:27 PM #2
Hi.
The drawings look pretty impressive. That would be great when built.
Have you considered adding a window in the seated area?
What type of fish do you plan to have?
If koi, than a 20k pressure filter will not be anywhere near enough to deal with the waste produced by koi.
If having koi, a drum (mech. Filtration) followed by a moving bed filter (bio filter) would be ideal, although other options exist e.g. sieve filter (mech. filter), vortex (mech filter), anoxic chamber (bio filter), nexus filter (mech. And bio filter).
Another thing to bear in mind, overspec any pump or filter. So if a pump says it shifts 20k lph, that is usually based on there being no backpressure/head loss. As soon as you pump water through pipes or above the pond level you will get less than the stated output.
Same for filters. If a filter says it can handle 20k lph, that is probably only if the water is clean (which it won't be). So whatever the stated flow is you need to add on 30 - 50% extra to ensure the filter can actually handle all the waste produced by the fish.
In terms of adding a shelf for plants.
Koi tend to absolutely destroy plants. But if the pond is sectioned up I.e. a series of connected smaller ponds, you could have one that is plants only, that would be fine and actually work as a good bio filter.
Also If you add a shelf, that would give herons a nice place to do their fishing from, so it's best not to have shallow shelves if you can help it.
In terms of bottom drains. You could not connect them. Because if you have one BD for the lower pond and one for the higher pond and they are connected, the water levels in the two ponds would level out i.e. the water level would drop on the upper pond until it was the same level as the lower pond. I.e. the lower pond would overflow.
Based on your drawings, you want the BD for the lower pond feeding back into the upper pond on one set of filters and pumps. And then a BD on the upper pond to be on a separate loop feeding back into the upper pond.
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04-11-2024, 12:33 PM #3
Also in terms of a skimmer, if the upper pond overflows into the lower pond, you probably won't need a skimmer on the upper pond (as theoretically anything floating will end up in the lower pond, providing it can actually get over the spillway).
So you may want a skimmer on the bottom pond rather than (or in addition too) the top pond.
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04-11-2024, 02:06 PM #4
Thanks so much for your reply, and especially for preventing me connecting two drains together - I obviously wasn't thinking straight.
It also looks like I'll need to upgrade the filtration if I want to keep Koi, so I'll get it built with the gear that I have and add smaller fish to begin with, then upgrade to larger fish and filtration later on. Presumably I'll be able to add larger pumps and filters without changing pipework etc.
I'll see how I can section it up now though (plant sections / fish sections) as that won't be easy later on. Maybe I could still have small plant shelves on the fish-free sections, unless there are better solutions for plants that are mostly above the waterline?
I had thought about adding a window where you suggested, but at that time I was also considering underwater lighting. On reviewing comments on this forum though I've since changed my mind about the lighting and now plan to have external lights shining down onto the pond, and wonder if there will be much to see through a window. I also wonder how waterproof it could be made, and how often it'll need to be cleaned.
Also, noted on the skimmer location - another error I would've made - DOH! Floating debris will go over the spillway, but I also need to use something that prevents the fish doing the same - would you normally use some kind of vertical mesh wall, full width and fully height, stopping just under the waterline?
Sorry for the continued questions.
Cheers!
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04-11-2024, 03:15 PM #5
I think a 60 cm pond depth won’t work for koi. Do you really mean 600mm?
You would get huge temperature fluctuations.
It would also allow a heron to easily fish for all of your fish stocks.
Your design also doesn’t seem to allow for having gravity fed filters.
Pressure filter would barely be enough for goldfish, definitely not for koi.
Gravity fed filters need to sit at water level, and you then pumpt the water from the filters back to the pond.2016 new 6000 gallon pond
https://www.koiforum.uk/pond-constru...ghlight=feline
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04-11-2024, 03:44 PM #6
I think you have kind of put the cart in front of the horse...
you have designed a pond, bought the components and are now asking for advise...
It looks like an expensive and complicated set up build wise with sunken seated area, and doesn't have the necessary filters for koi keeping.
the basic design principal of wrap around pond, bridge, steps, and sunken seated looks good.
but imo you need a depth of at least 4ft for koi 3ft is possible but would require heating to prevent swings in temperature.
and a reasonable width in places (2 meters) to allow the koi to swim freely when full grown between 60-80cm
some demensions on the drawing would help, how wide is it?
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04-11-2024, 04:16 PM #7
I did mean 600mm depth as I wasn't originally planning for large koi, but it could still be adjusted at this stage. The ambient temperature fluctuates between 16 and 28 degrees Centigrade (it's on the equator) so presumably temperature isn't an issue, but predatory birds could be so I'll need to consider that.
I was planning to use a pressurised filter as I can't have anything at or above the water level, so it seems I'll need a larger pump and filter if I want koi at a later time.
Thanks!
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04-11-2024, 04:20 PM #8
I definitely have got the plan back to front, but there was some thinking that went into the equipment, even if it's now proving to be not quite right .
The width of the pond is 1,7m all round, the "arms" are 3m long and the long straight section is 10m.
Thanks
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04-11-2024, 05:06 PM #9
If you wanted to upgrade your filters, you will almost certainly have to redo your pipework. I think it'd be a mistake and you'd waste a lot of time and money by making do with small filters now then trying to upgrade them later. Koi filters are big. Plus you need to allow plenty of space for all the pipework, and it needs to be easily accessible so you can clean them etc...
In terms of location of filters, the area to the left of the pic (next to where it says inlet), or the top right (at the top of the stairs) would work for gravity filters.
But if the filter pit is below ground e.g. under decking, you'd need a way to be able to lift the decking so you can easily access the filters. With emphasis on the word 'easily'.
Your filter pit will need to be bigger than you probably envisage. For example I have a shed that is 6ft wide and about 7ft long and I can only just get all the filters in it.
In terms of lighting, definitely don't have submerged lights. They're way more of a faff than overhead lights. If you added a pergola over the seated area and the pond area adjacent to it, that would provide a perfect place to add overhead lights so they illuminate the fish from the right angle from where they will be viewed i.e. you don't want the lights at the back, as it will put the front of the fish in shadow.
In terms of seeing the fish, that will depend on what filters you have. You need filters that can extract nearly all of the solids in the pond. That amount of water filtered through a tiny pressure filter would soon get murky with all the waste. Plus you'll need a UV filter to avoid the water going like pea soup from free floating algae.
Have you costed this project up? I can see it very easily going over £20k. For example, due to the irregular shape of the pond I'm not sure a box weld liner could be made (I maybe wrong on that point) so your main option to line the pond will be to fibreglass it, which isn't cheap, even if you did it yourself (which is what I did).
Other things to consider are how you will get water supply and electricity to the pond, and also how you will deal with all the dirty waste water (as you need to do a fair amount of water changes to keep koi healthy).
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Filtreau 25 & bio unit
I also agree with Al and John, mains water for cleaning the drum is the best way to go, providing...