Most of you know how my system operates and what my mission was. As the koi grew a lot this season they have overwhelmed my mechanical filtration capacity.

I need to expand that now. I have proofed that it is mechanical by some emergency measures I have put in place ... synthetic wool in the waterfalls and streams and the refurbishing the two green tanks on advice from Paul.

Now I need to put a system in place to replace the wool that is everywhere

Hi Colyn
Would you please recap on your water volume and elaborate on your current mechanical filtration, amount of fish plus amount of feed per day. Also % water change a week will be helpful.

Colyn as you know you have one huge volume of water to filtrate. It is obviouse to me that you cant turn the water in an hour without increasing your montly electricity bill.

I dont think any of the tranditional filtration systems are going to work properly just because of the sheer size of the water volume. Im not saying that the normal medias and methods wont work im just thinking that the cost is going to be very high if its going to be implemented.

I dont have an answer for your problem yet but wish to ramble on a bit more.

You have two challenges as i see it:
1. The time it take to turn the body of water over.
You have to try and increase the flow rate so that you take the solids out faster than whats its being produced....thats what we all aim for. Because of your setting and enviroment you might not have control over how fast waste is being produced. Most koi keeprs only have poo to worry about when it comes to waste, some of us can even add leaves to the list but you have poo, leaves, plants, frogs, bugs and a whole ecosystem around your pond that is contributing to the waste. So i think the idea of a sparkling clean koi pond is out of the question.

2. The amount of time to be spent cleaning the filters.
You have 2 choices under this heading. You either have bigger filters that you can (dont have to) clean over a longer period or you can have s smaller filter that you have to clean more often.

Maybe you should start by telling us what mechanical filtration you have. I can think of a few people that have big ponds as yours and they all have 7-10 swimming pool pumps running continuesly. Ill see if i can find our more how to filtate such a big body of water.

i contact a guy called Luke frisbee on bito. He has a huge pond that most of the guys refer to as a lake. He is replacing rougly 4680 liters of water a day. The water comes from a borehole. He says he does not know the exact volume of his pond but its over 200 000l.

His mechanical filtration constist out of a racecourse of 16m x 1m x 1m filled with diffirent grades of mechanical filtration. His main filtration is 300 x 0.6m long brushes and pvc straps.

I think a racecourse filter is an up and under filter but im not sure.

His turn over rate is also very high at 111 000l of water per hour. He suggested that you add a bog to capture most of the big solids aswell.

Hi Colyn,

I suggest you use what you have but add a SINGLE large chamber onto the existing system. This would be an increased mechanical filter. Use the same pumps etc.

The various bits and pieces of wool etc you have all over the place - such as in the streams - could be consolidated in this single large chamber.

So being creative would be the answer. You can use everything you have. It’s just the placement of this chamber what goes into it and a few design parameters. We can discuss these to get them to work.

Then - how is the algae control going? This goes hand in hand with mechanical filtration.

Regards,
Chris

Let me explain some of the major elements in my system.

I have around 120,000 litres of water in circulation.

My system is designed in such a way that ALL my water enters the system through the waterfall at the head of the pond system.


There are three ponds in series cascading into each other to the bottom of the garden.

Pond #1 and #2 each has attached to it a trough system that is fed by the 110mm bottom drains and the outlet of the troughs are tuned in height so that in the event of a powerfailure the level will drop around 20mm and then stop.

The troughs have a mixture of stone bags, nylon brushes and shadecloth balls in to do the mechanical and some bio filtration. Both trough systems also holds plants.


Pond #2 has a similar trough system.

The ponds are all joined by a stream ... 600mm wide and the streambeds are packed with quarts rock and some plants.

At the bottom all the water ends in the Veggie Pond. Roughly 30,000 liters.

This pond contains plants and structure built with bags of stone. This pond aalso contains goldfish, kurpers, pengasius, mollies and platies with 4 oscars.

Each specie is playing a specific roll and we have zero issues with mosquitos etc. I do have a problem with the kurpers currently in the sense that they breed to much. Last week we harvested around 10 kg of kurpers from the pond.



Two shots of the veggie pond. The condition of the plants tell me that it is working and that I have lots of spare capacity.

Mechanical filtration is done by two troughs of bagged stone.

At the end the water lands in a sump and from here it is pumped to two 1,000 liter tanks. These tanks are filled with bags of shadenet balls and 30% with bio-balls.

From these tanks water runs by gravity back to the waterfall.

Anything I do must happen in main stream so that I do not interfere with the volume balance. This means if I should add say trickle towers, I will have to do it BEFORE the pumps and if I want to merely polish the water I will need to do it before the waterfall.

The other option is to install a separate loop that circulates water from the pump chambers and drops the water back into the sump ... this will add pure rotation on the side of main stream.

I am beginning to lean in this direction because that system can then be stopped under low stress conditions.

Let me here your ideas ... let's be innovative

Yes Chris I agree with you ... the reason why I am thinking about a secondary "polishing" loop is because a smaller pump that need not cope with the 5m head will push high volumes through the "polishing" loop.

As for the algae ... I have the two UV's which I think is ample if combined with the algae eating capacity of the kurpers and goldfish. I see this seasonal flare up but it looks like the shear mass of my bio engine is of such that it strangles the algae rapidly as the day heat up. I am not too concerned about that. My problem is getting the dead algae out of the water body. Something that I only managed after the temporary introduction of the wool in the streams and waterfall. Initially we had to clean the waterfall wool three times per day and nou it has been running for 4 days and is fine. This tells me that the tanks are up to speed and the overdose is out of the system.

Hi Colyn,

I think I should really get in my car and drive down to Nelspruit to look at your system ....

Questions:

1) at the bottom of the whole system - is this where the pump sucks from and then sends the water to the waterfall at the top / beginning of the system? If so - size of pump (you have probably told us already but for me please). Also size of this chamber and what is in it.

2) each pond has water diverted through your stone chambers to "clean" the water? So each pond has its own 110 pipe gravity feeding this system on the side of the pond? And then this feeds back into the same pond?

More questions to follow after some answers from you.

Please don't make any changes yet. We may have a simple solution. Something like 6 x Nexus filters, 14 x compressors to supply air (to the ponds, filters and surrounding atmosphere), 24 sand filters in parallel, 12 vortexes with special media placed 3 x 4 in sequence and parallel, and a small bag of barley straw to control the algae.

Regards,
Chris

Chris Neaves wrote:

Please don't make any changes yet. We may have a simple solution. Something like 6 x Nexus filters, 14 x compressors to supply air (to the ponds, filters and surrounding atmosphere), 24 sand filters in parallel, 12 vortexes with special media placed 3 x 4 in sequence and parallel, and a small bag of barley straw to control the algae.

I really hope this is meant as a joke.

As i said ealier...

Quote :

I dont think any of the tranditional filtration systems are going to work properly just because of the sheer size of the water volume. Im not saying that the normal medias and methods wont work im just thinking that the cost is going to be very high if its going to be implemented.

For the amount of water you have a simple solution must be found with a low cost. I guess brushes as suggested by Luke is not a bad idea but it is going to be costly. Otherise you just need some obstacles in the water at the end of the system to catch the solids. Several sheets of Metala matting might do the trick aswell.

Hi Colyn

Whish I could go down there with Chris to see his suggestions and also learn something more.

I think getting the muck out of your water is no problem but to clean that system will be the challenge here.
Anyway I dont think brushes is such a good idea they are more bio than mechanical if I am correct and are costly. I sell plastic shavings in baggs, which works well for both. Dont know if Chris's idea's will incorporate it though.
I just love Vortexes for mechanical but they must be filled with a media correctly.

Quote :

1) at the bottom of the whole system - is this where the pump sucks from and then sends the water to the waterfall at the top / beginning of the system? If so - size of pump (you have probably told us already but for me please). Also size of this chamber and what is in it.

At the bottom the water ends into a sump that is roughly 1.4m x 1.4m x 2.0m deep. In this sump is 3 submerseable pumps. 2 Pumps to the green tanks and 1 pumps directly to the waterfall. The latter was done to push the flow up a bit, there is 3m head difference and the waterfall pump is delivering too little if it needs to pump to the tanks.

Quote :

2) each pond has water diverted through your stone chambers to "clean" the water? So each pond has its own 110 pipe gravity feeding this system on the side of the pond? And then this feeds back into the same pond?

Yes it is 110mm into the stone/plant troughs and 50mm out. Pond #1 drops the water into Pond #2 and Pond #2 drops the water into the collection trough at the end of the Veggie pond.

Some may question the 50mm but a 50mm pipe running at full speed moves a lot of water. Any higher speed and you dilute the effectiveness of the over and under efficiency of the trough system plus you do not allow the plants enough time to do their thing.

The troughs do have the facility to be flushed properly and by blocking the 110mm and allowing the troughs to run down I get enough suction to flush the 110mm from the pond properly. I am happy with this system and they work well. Looking at the volumes of dead algae that I collect in the troughs I am confident that this part of the system works.

I have chamber just before the pump sump that every drop of water in the system passes through and I could use this for the final polishing. Currently this chamber plays an important role in catching runoff when the power fails but it is a logical place to polish.

Wayne mentioned a bog ... well the design of the veggie pond is of such that it acts as a bog already and as the plants spread this will get more pronounced.

Neville ... give me some idea on cost of the shavings please and where are you based.

Flushing and cleaning the various components requires some manual labour and it takes me and my garden engineer about 30 minutes once a week. We open the drains on the troughs and flush the rubbish out with a hose pipe. The big tanks gets stirred and drained.

The wool sheets gets washed every day and it is a pain. My whole system is designed in such a way that none of the components will lead to a overflow/spill if the filter elements gets blocked. If they get blocked/choked then the water merely runs over it and carries whatever is in suspension with it.


PS ... Chris ... all those things you mention ... ... trust me I have had moments of insanity and thoughts that went along that route.

Thanks for the comments ... I am sure we will end up with a practical and economical sollution.

As I am typing here my water in the ponds are basically gin clear and the bottoms are clearly visible.

Hi,
I hope I get the quote correct -

Quote :

1) As I am typing here my water in the ponds are basically gin clear and the bottoms are clearly visible.

This may seem a strange question at this stage - based on your final sentence - my question is why try to fix something that isn't broken?

Your fish are alive and healthy - your water, in your own words, is gin clear - so there is nothing wrong with your system.

It may not be a conventional system but it certainly works.

The only suggestions I have is to remove the papyrus plants - they grow like hang, their roots collect masses of fine material and these same roots go anaerobic very quickly.

Then I suspect that because each pond has a part of the water diverted through the filter system on the sides there is a dilution factor. In other words not all the water is filtered and therefore it will never clear. Having said that you tell us your water IS clear. So the system is working but goes through cycles as the algae grows and dies back. The single cell suspended algae can reproduce itself about 30 times an hour in the sun. So the clarity of the water can vary within a day or two.

I also suggest you move the wool in the streams to the chamber at the bottom. Stacking it in such a way as it will not block the pumps. You probably are dropping half of the organics trapped in the wool back into the pond when you remove it to clean it. Perhaps loosley packed in bags. Never pack material tightly in veggi bags. This causes the water to move around the outside of the bags because of the resistnce in the middle of teh bag.

You can then remove these bags and wash them with a hose pipe or pressure hose.

Question - does all the pond water go to the top where the water fall is?

Hope this helps,
Chris

Thanks Chris ... I will answer some of your questions now here and respond to some of your comments. Later I will go and walk the ponds and do some shots that will give you all more information.

As for the water being clear currently ... yest that is true but the solution is not elegant and needs to be redesigned.

I also need to design for next season when the fish mass will be a whole lot more than this year ... thanks a lot to your Shogun which they devour. (BTW Pierre will talk to you during the week ... need to stock up again.)

Yes part of the water pass on to the next pond via the trough and the balance go via the stream. That is true for both koi ponds.

All water goes over the waterfall and finally through the collection trough before the pump sump.

I don't want any filter material in the pump sump. It is almost 2 meters deep and will be a hellhole to maintain

Take a look at this shot of the veggie pond.


The pond cannot be drained completely ... once a year we stop the system and shake the bags in which the plants grow, shake and rinse the floating root clumps and dislodge as much of the "black" powder as we can. We then sweep as much solids into the far corner and let is stand for an hour or so to settle. Then we pump the pond by sucking as much as possible of the debris on the floor out.

All in all around 15,000 liters of water is dumped from this pond in the process and if any serious "gif" was unleashed during the cleanup it will be well diluted before it starts to circulate again.

The biggest mistake I made was not have a second bottom outlet in the main section of the veggie pond. ... now I need to pump or siphon the muck out.

I will keep an eye on the papyrus.

Tell me more about the anaerobic issue please.

PS ... I got distracted and walked the ponds before I posted so here are the shots.

Hi Colyn,

A suggestion - if all the water in your system eventually goes over the water fall at the top the simple solution would be to put any ideas into effect here. It would be the simplest solution because -

1) all the water goes there
2) all the pipe work is in place
3) Start here to clean all the water for the pond

Here is a crazy suggestion.

Very basically -

1) Cut the pipe work to the water fall and direct it into the top pond. This will enable the system to carry on functioning.

2) Remove the water fall - completely.

3) Build a single large chamber in place of the water fall - on ground level. Build it correctly with the necessary re-inforcing etc.

4) The design of the chamber and what goes into it is critical. (more on this later)

5) Re-pipe the pipes to deliver the water to the bottom of this chamber.

6) Let the water flow up-wards through your chosen media and then over-flow back down a water fall you build infront of the chamber. (the way the media is packed and the internal design of the chamber is very important).

7) landscape around the chamber with soil and plants.


A picture of a single chambered filter with a waterfall in the front.

Thanks Chris ... you have given me an idea ...

Tell me this ... what type of media would one put into a bottom to top chamber configuration ?

Will such a chamber clean the water properly ... iow remove all the suspended particles ?

Thanks.

Hi Colyn,

Make the chamber in a L shape. Something like the picture in my post. This will help with the structural strength. Also make it fairly large.

Slope the floor to one side and at this point install a brass gate valve. Say around a 63mm valve. Plastic valves are fine but this chamber is going to collect a lot of solids and every time you open a plastic valve a minute amount of git gets into the ball and there is a a lot of wear and tear, in a few years time you have a leaking valve.

Water proof the inside of the chamber with something you are familiar with - but not the bitumen type sealants. Rather Coprox or even pure cement.

About 20 - 30cm off the floor you want to install a grid to support the media. This grid will create an open space at the bottom. The hydraulic load on the media (from the water rising in the chamber) will be even. (a very important point in the design) Also - and this is very important - when you flush this chamber you must drain it completely and rinse the media down from the top. As the water moves down through the media it will suck the trapped solids through to the open chamber at the bottom and they can be flushed to waste. Its the last few centimetres of water moving downwards that does the trick. Never leav any water in this chamber when cleaning as you will always have quite alot of solids remaining and being pumped back into the pond.

The piping from your pump - bring it over the wall and not through it. Take the pipe or pipes down to the floor under the grid and place a 90 degree elbow on it / them so the water enters horizontally and not vertically - this is for long term wear on the cement. Also to create a circulation under the grid.

You can use any medium. Shavings in vegetable bags will work well. Wash throughy with hot water before using. But you must pack the shaving loosely in the bags so that the bags lie more or less flat and not stuffed full and are round. Then you pack several layers at right angles to each other ensuring there are NO gaps what-so-ever for the water to take the path of least resistance. A good 4 layers.

You can make this about 50cm - 60 cm deep. So rather have a larger single chamber. This will slow the water down as it moves through the media. Also if the media is not too deep it will not clog but it must be deep enough to trap the solids.

Back to the piping. I suggest you bring the piping over the side because you can use a valve system at the edge of the chamber to reverse the flow from the pump. You close one valve to the bottom and open another which will direct the water to the top of the chamber. Use a length or two of Creepy Crawley piping on this outlet and you can use the full volume of the pump to back flush (i.e. clean properly) the media when all the water is out of the chamber.

The out let from this chamber can be directed onto the garden. You can even use a long pipe to direct it to different parts of the garden. The plants will grow like hang.

More thoughts - there are lots of things to use to make a grid.

Leave a space of about 20 - 30cm for settlement above the media.

Regards,
Chris

Back washing a single chamber by reversing the water flow from the pump.

On the left hand side of the picture is the overflow back to the stream / pond.

Thank you Chris ... I will chew on this post for a bit ... I need to see the whole thing in my mind clearly and then see it in my system.

Hi Colyn

Ek het vir jou n PM gestuur. Laat maar weet.

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