Pond construction

Hi, I am currently in the process of digging out my new pond

I would like to have koi carp so water quality is a big factor.
The size will be 12' x 7' and approx 6' deep in the middle.
The old greenhouse has gone so I have decided to use the space because it saved on the digging a bit and removing the old bricks. The pond will be raised slightly above the garden level 10"-16"
I was going to use a pvc liner as I am on a budget with this project. But after reading up a bit I am now going to use a butyl rubber liner.

I will be installing a pump and filter system that suits the size of the pond.
Need some advice on the pump & filter system.

After further reading I decided to add a bottom drain. This is where I am not sure about the best way of piping out the water?

A waterfall of some type will also be installed.
Is there a way to design the waterfall to assist in the cleaning of the water?
ie. gravel or reed bed etc.

I will post up pictures as I progress with this project

If anyone can give me any tips I will be grateful

you have a long way to dig.

a bottom drain should be installed in the centre base of the pool with the surrounding area sloping downwards towards said bottom drain.

The bottom drain itself should be mounted in concrete.

the bottom drain should be connected to a custom made filter system, round ones are best (its called a vortex chamber) the idea is the water comes in at the top and exits almost at the bottom. any solids sink to the bottom.

from here it should then go through various chambers of filter media (your choice) and then back to the main pool.

You put a suitably sized pump in the last chamber, this pumps water back to the pond via a waterfall or a venturi nozzle, some do put cress in this and call it a veg filter, yes you can eat the cress, (great with egg)

The pump must be capable of pumping the whole pond / dfilter volume once every 2 hours.

By putting the pump in the last chamber it sucks water through everything else drawing water / solids in through the bottom drain.

You also need a 2nd pump sending water through a UV,

you cant use the main pump as the water flow through the uv will probably be too fast to be of any use.

all filter sections and the main vortex chamber should have their own bottom drain leading to a sump which either has a soakaway or a sump pump so you can pump it to waste.

it is amazing the colour of the water when you pull the plug on the bottom drains.


If you are on a budget I would seriously consider building a normal pond, as they are much cheaper since they dont need all the filtration to be as big and can use small filter boxes

You dont also need to keep an eye on the oxgygen, amonia levels

Koi ponds look nice, but in all honest cost a never ending fortune.

Pond filter info clicky

Theres not a lot to add to what Beezer has to say.

Re plumbing up he bottom brain, fit a valve so that the ilter n be isolated from the pond for maintanaceand also a Tee with say 2" valve just beforeheminvalve so the sediment that builds up n the BD pipe can be discharged.

Use the BD to feed the filter under gravity into a settlement chamber (pref Vortex) and this will emovemost of the solids before the filter and having the pump at the end of the filte run means its pumping clean water so won't keep clogging.

It is possible to add vegitation to the waterfall header, this will elp to remove nitrate which is a bi-product of the filtration process and also a good feed for blanket weed.

Fit the larger filter than that for the capacity of the pond, you need to consider stocking rate and amount of food, not just volume. Also worth looking at the Nexus filters which don't take up too much room, not cheap though.

Couple of pics of my pond under construction here if you are inerested

Jason

Jasonb, i looked at your pictures, either thats a clever liner or you fibreglassed it, (but i suspect its a liner, but my monuy is on fibreglass)

For joineruk's benefit would i be right in saying all the kit cost around £2k, which i think is going to be more than joineruk may think it will cost?

Rendered & fibreglassed

What bit of "kit" are you refering to?

Jason

I dont want to cause any offense to anyone, but would you agree that building a koi pond is "not cheap"

Its certainly not cheap, but if the OP really wants a koi pond its better to do it right at this stage than rebuilding 12-18months down the line. Mine cost me about £1.25 per gallon when I built it around 8yrs ago,its only a small one at 3500gal.

You also need to work out the running costs - couple of water pumps (look at the wattage when buying), air pump, UVs, sump pump, cartridges for incoming water filter. Then there is food costs and any water treatments should they be needed and thats before you start thinking about heating the pond

Really depends on what you want out of the pond, a few Koi that appeal to you that you can enjoy in clear water or high quality koi that you want to grow on and develope even to the extent of showing them. I just enjoy what I've got, not show winners but thats not what floats my boat.

Jason

Thanks Jasonb i didn't want to say any cost since i have not built a loi pond, but it does sound about the same as to waht others have said.

I wonder if the £4k (ish) is what joineruk is aware of.

joineruk, perhaps you may want to have just a goldfish pond?

Some excellent info there

I would like to have koi so I am going to use a bottom drain.

Is there just 1 outlet pipe from a bottom drain?

The pond when dug out will be approx 2800 gallons.

What pump should i use for this spec?

Many thanks for the help

yes

one that can pump 14,000 GPH

thing is, i just checked, one site says your pond will hold 110,880 gallons

but two others say close to 3139 gallons

breezer said:

one that can pump 14,000 GPH

Click to expand...

At that rate the fish will be sucked down the bottom drain Breezer there are 6.25 gals to cu ft, you are working to 220gal per cu ft, its 220gal = 1m3 or one tonne of water

12x7x6 ft x 6.25 = 3150gal so allowing for slope etc 2800 is about OK

You need to turn the pond volune over approx once every 2hours so 1400gph is about right. Look at the pump specs, a lot of the cheap submersible pumps have a high wattage. Decent submersibles such as Oase and external pumps like Sequence have quite a low wattage, they may cost a bit mor initially but over a year or two wil pay for themselves. My pond is 3500gal and I us etwo central heating circulators which when on the higest setting will flow approx 800gal each and use 50watts each.

Bottom drains only have one outlet as they can only flow a certain amount of water between the base of the pond and the top. One BD with a 4" outlet will be fine.

Jason

Jasonb, i didnt think it sounded right either, but thats what one site said.

how ever i was editing while you posted.

i have just checked a 3rd site and it agrees with the other two 3139 gallons or 14126 litres.


but he still needs a pump which can turn over 1/2 the volume / hour (or bigger)

I would say get an Oase Aquamax 8500

yes the 8500 should be about right allowing for pipe friction etc. Can always split the output into two for the UV and a separate tangental return to get the pond water spinning down the plug hole, sorry bottom drain

I've got an Oase that must have run for at least 15yrs non stop first on an old koi pond and now on my goldfish/plant pond. Dam god pumps

Jason

Some excellent advice I now understand the job in hand

But I was hoping to have a pond with a pump and bottom drain and thats it.

I will fit a bottom drain and have a inline pump to supply the top pond which could be as big as 3mx3m and 0.6m deep. The top pond will be filled with gravel for reeds to grow. The top pond will be about 0.8m higher than the main pond. The top pond will be cramed with water cleaning plants.
Have a look Here to see what I intend to do.

After find an article Here I thought this may be possible.

I know you guys have obviously spent all that cash for a reason.

But is there a chance this may work

Undergravel filters are really 20-30year old technology even upflo ones.

There are two main problems

1. without supporting the gravel media on a raised support and providing a means of draining the void below the filter media will need to be cleaned every 12-18months. This involves digging it all out and washing by hand (been there, done that) and you will then have to wait for the filter to mature once the water is flowing again. Even then you will get "tracking" where the water finds an easy route through parts of the filter and no water flows through the rest.

2. If you suffer a pump failure or a long powercut the bacterial in the filter will break down with the potentioal to poison the fish.

The idea of a bottom drain when used as a filter feed it to take all the solid waste to a point where it can be removed from the pond easily, rather than feed the filter with a load of fish s**t. You will make the problem worse by pumping these solids as the pump impellor will act as a liquidizer.

At the very least go for bottom drain to vortex/brush chamber then upflow through a suspended gravel bed. Or BD straight to waste and feed the filter with a mid water outlet.

If you could see what I flush out of the drains at the bottom of my filter chambers each day you would not want that going into a gravel bed system.

Vegitable filters are fine as a supliment to a decent system but what are you going to do for six months of the year when the plants are dormant but your fish still want feeding three times a day?

Depth does not make a lot of difference with undergravel filters as anymore than 6" of gravel will depleate the water of oxygen that the bacteria need to work, even with air pumps 8" would be the max depth of gravel needed. While talking gravel, if you go with this option don't use pea shingle from a builders because its cheap get cantabury spar which has a much higher surface area for the bacteria to cling to.

Jason