[b]Please help

How does one calculate the volume of a circular pond?

and,

How do I calculate how much flow I would get from a bottom drain? (In this case on a40mm pipe?)

Thanks

To calculate the volume is easy and will be done as follows :

RXRx22/7 = Area x the depth of the pond.

If the diameter of the pond is 2 meters and the pond is 1 meters deep for example it will be as follows :

1x1x22 devided by 7 = 3.143 m2 X 1meter for the depth and your volume will be then 3.143 m3 and that equals 3143 lt.

The flow rate for the pipe I can not help you with sorry.

I know somewhere on this forum there is a pond volume calculation sheet but don't find it know

The flow rates can be calculated with software available for free trial download at [You must be registered and logged in to see this link.]

To calculate the pond volume, you can download my calculator (excell format) from here: [You must be registered and logged in to see this link.]

Example of my calculator:

[You must be registered and logged in to see this image.]

Thank you

If the trial version of the pipe flow software does not work for you, you can also use the calculator at [You must be registered and logged in to see this link.] for free.

There you will see that you should not use a 40mm pipe as a connection between your bottom drain and settlement chamber. The loss of flow rate on a 110 mm pipe (based on a 3 meter pipe to your settlement chamber), will be almost 8 times less (depending on your pressure at the bottom drain/size of pond)

The 40 mm pipe might also block from time to time, whereas the 110 mm pipe should never block.

If you only have one 40 mm pipe to your settlement chamber, you will probably suck it dry with a 5000 liter/hour pump.

Example:

3 meter pipe @ 100 kpa

40 mm pipe = 4 536 l/h
50 mm pipe = 7 050 l/h
110 mm pipe = 34 200 l/h

Hi,

The above gravity fed pipe flow rates are absolutely critical when calculating flow rates of the whole system and should always be kept in mind.

This is excellent advice and rather cool calculators.

So many ponds are well designed but fall short when it comes to piping diameters. All your calculations go out of the window when you use small pipes.

Always go for the faster flow rate where ever possible. The faster the better.

Regards,
Chris

Thanks for the advice guys...


Mmmmmmmm.......What do you suggest I do..

My question stems from the fact that I am looking at converting a 5 000L water tank into a koi pond.

The bottom outlet is 40mm, therefor my question. The tank dimentions are as follow (before I convert it) 1,840m (wide) X 2,200M (high). Basically what I want to do is cut the top of, burry it half way & brick up around the second half & clad & cope.

I want to take the bottom drain pipe & have gravity flow to a settlement chamber, and then either suck the water from there, or better yet, let it flow to a second chamber (via gravity) and then suck the water from there.

These kind of tanks have a second outlet close to the top, where I can add another 40mm pipe that could act as a surface skimmer to the settlement chamber as well.

Will it have any effect if I stepped up the pipe after the 40mm bottom connector to a 50mm or bigger pipe??

Or should I look to see if I can convert the bottom drain connection, from 40mm to 50mm? (I dont know if this will be possible?

Or add the "Skimmer outlet" from the top??

Please bear in mind that the pond volume would roughly be 5000L.

Thanks for your valuable advice

My advise is to blank of the existing outlet or other wise use it as a jet inlet at the bottom of your pond, then I would buy a 110 mm bottom drain for a liner pond and install ot I will rather go for the 110 mm route

Hi Shawn

On a 5000L water tank i would:

1. Suck directly from the bottom drain with a swimming pool pump.
2. Not bother with a settlement chamber or vortex system for mechanical filtration.
3. Use a Speck Magic 6 (250Watt) Pump 10 000L/Hr
4. Use a 2bag Koi Sand filter as mechanical filtration.
5. Place your biological on the return line of the pump
6. Enlarge the 40mm connector to atleast 50mm (40mm is for moffies Think Big) for the bottom drain.
7. Add a airdome to the bottom drain.

All of this might sound strange but a 5000L tank is small enough for this setup to work. The only downside will be that you will have to clean the pump basket more often than people with settlement chambers and that is also only if you have a leave problem.

Enlarging the bottom drain 40mm pipe to 50mm after the adapter is useless as the 40mm will be your restriction.

The 40mm pipe for the skimmer should be OK.

If you want to use a settlement chamber with vortexes and all that stuff you will have to increase the bottom drain line to atleast 110ml.

Cheers

Wayne

The connector on those tanks are on the side and not right at the (floor)bottom. Most of the junk will remain in the tank below the intended outlet to your chamber and will not properly work as a bottom drain.

It is quite easy to install a new tank connector right at the bottom of the tank leading to your settlement chamber and then your can either go the 50mm route and combine it with the existing 40 mm outlet, or just go the 110 mm route.

It is a matter of taking a jig saw, cut the circle, put some silicone on and insert the tank connector.

Instead of cutting the top off and end up with one narrow deep pond, I would rather cut the tank in half and end up with 2 x 1,1 meter deep ponds connected to each other with a 110 mm pipe, with a bottom drain (right at the bottom on the floor) on each. The fish will be happier and you will end up with more natural food because of the larger surface area, your will be able to see the fish better and the whole setup will look better. On the top half, you will just have to silicone the lid properly, turn it around and do your bottom drain with a tank connector on the lid itself.(deepest point)

I would consider something like this (which I considered at one stage for two liner ponds next to each other)

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This can be done below, above or halfway above ground level(boxed)

If you cover the setup with decking and only leave the two ponds open with a bit of an overhang and create lids in the deck for access to the settlement chamber and biofilter, it will look quite nice.

Does this mean you effectively have two ponds?

Yes, although they will have the same water and same filtration and the smaller fish can move around from the one to the other if the 110 mm connection has been used.

You will notice that the small fish will hide inside the 110mm connection when they sense danger.

Another advantage is that you can separate the two ponds from time to time, for instance when you have health problems and wish to treat only one or only a few fish and you do not have a seperate hospital facility.

You can also separate them when you wish to quarantine new fish in the one section, and open it up again after successfull quarantine.

Okay... mmmmm... lets see

I must admit your initial suggestions of the two pond concept, came at me completely out of left field

So thank you for giving me a bit more clarity on it, your explenation on why the 110mil conextion between the two ponds also makes allot more sence..(i.e. smaller fish swimming through) I reacon even my two biggest fish are now around (30-35cm) would still be able to fit trough??

I need to go and measure my space & see if I can fit two in, but assuming I can, I have the following questions;

1) What is the benifit of greater surface area?
2) You mention that there will be more natural food available? Why
3) Can anyone here suggest ways in which I can make this look like one pond? (i.e. do the coping so that it looks like a figure 8 or hide the middle by way of a fake bridge??) The only provisor is that it needs to be unobstructive as possible to the viewing of the koi from my deck.
4) can one make this system 100% gravity fed? (I would love to try and design something like that as I still have waterflow when our friends at Escom lets us down )

Other concerns
Submersable pumps in my book means allot more maintanace (Any other options) or how do I lemit this.
The two 110ml bottomdrains means the cost would go up quite a bit
But it might be worth it ??
Thecnically this means allot more cutting & sealing---- How do I do the 110ml connection between the two halfes of the pond? AND MAKE SURE IT IS LEAK PROOF??

If I want to be able to seperate the water volume between the ponds I think that would effectively double the cost??


As you would need to put a valve in the 110ml interleading pipe? Have two seperate settlement chaimbers & returns for it to be effective ?? Else the water will just mix in the settlement chaimbers? & If you use a pump driven system, two pumps

Greater surface area = more sunlight and thus more growth of organisms and warmer water = more natural food = better growth rate.

Submersible pumps does not mean more maintenance. It is a cheaper option for a small pond and the electricity bill is much lower. You only need one for both ponds @ 16o watts/5000 l/h

The system suggested is gravity fed.

You can do the connection of the two ponds with two 110 mm liner pond bottom drains.

Because each system will have only 2500 liters, a 50 mm bottom drain together with the 40 mm existing (side) connections on each system should be good enough. ( 2 x 50 and 2 x 40 for only 5000 liters)

The costs will not double. It is the same tank, still one settlement chamber, one bio filter, one pump in the bio filter chamber, pulling water from your settlement chamber and back into both ponds. Only a few extra connectors/piping.

You don't need a valve on the 110 mm piping. When you want to separate the two from time to time, you just put PVC ends on the bottom drain, inter connecting pipe and inlet and when you want to combine it again, you just remove the ends again.

When you need one for hospital/QT tank(which is not going to happen often), you can get away with water changes and an airstone in the one system that are being used as hospital/QT.

Obviously the ideal would be to have the possibility to run the two systems totally independant if required. It depends on your budget.

I suggested a deck because with a deck over the two systems, you can easily create the effect of one pond with a narrow bridge over the pond, and it can blend in with your existing deck. In other words, you box the whole system and just cut out the areas on top where the two ponds are, and leave an overhang to hide the ugly tanks. Then you cut out access from the top to the two filters and make lids with hinges with the wood that you cut out.

I measured up my space, it doesn't allow me two use the two halves concept no matter how I try and configure the two haves.

I checked again with the supplier of the water tanks, I could possibly consider using the 5500L tank.

The dimentions are different it is 1.750mm (high) & 2200mm (wide), with a bit of luck I should be able to make this fit.

This is a more expensive option as this tank is roughly R 1 500.00 more expensive than the 5000L. However the surface area is allot (43%) bigger, and it is not so deep.

This will give me 3.80 square meters as aposed to 2.65 squares.

I would then probably consider one 110mm bottomdrain to a settlement Chamber, to a bio station then perhaps the submersable retunring to the pond.

I was thinking of using the top 40mm outlet as a surface skimmer to the setthement chaimber, but what do I do with the bottom one?

What do you guys think about this system?? Please crit!

Thread moved to "Building pond with water tanks" Please continue there.