Hi everyone...
Yes, just about any media will work in terms of providing the "housing" required for bacteria to grow on..... and yes, there are serious considerations to take into account.....
If you choose to use a plactic media - make very certain that the plastic used is chemically inert! This is critical otherwise in the long term you WILL definately kill your koi! Also ensure if using a moving bed media that its hydrophilic performance is right.....
The other main criteria is cleaning..... yes, whilst you can use pieces of brick and stone.... you have no way of cleaning this material...... over time the media WILL clog and channeling will start to take place..... then all you need is one major power failure and I can almost guarantee you 99% you will have a bacterial infection second to nothing in your pond!
When I first started out I had 3 Ponds running and I used sandfilters and high pressure bio filters... I had bottom drains that T into single lines all 50mm and were pumped to the sand filters - this setup was clearly a disaster and never worked and I constantly had water problems and fish health problems...... removing the drains felt like too much of an effort and at the time I thought it would be costly - so I built a massive settlement chamber which then overflowed into massive brushes chambers - one was more than 12m long..... I spent a fortune in purchasing stainless steel brushes......... I then pumped the water to the settlement chamber and brushes chambers.... this was a bit of an improvement, but required so much time in cleaning, and still was not 100% happy! So I did not stop there... I went out and purchased heaps and heaps of Matala.... and again spent a fortune (at this point I was adamant that I was going to have the perfect system...and my husband was close to divorcing me......)....... and all I did was add to the time that I spent cleaning the ponds.....
So I finally did what I should have done right from the start...... I removed the fish, drained the ponds.... cut open the floors - removed the 50mm drains and piping..... installed proper 110mm drains each with their own separate line and purchased NEXUS's... I have never looked back.... I was then subsequently banned after this from purchasing any more filtration
Luckily for me it worked.......
So if I look back now.... I realise that had I done the right thing from the start... I would have saved literally hundreds of thousands of rands.....
When looking at filtration the important thing is to make sure that you have looked at the design of your pond...and there are certain things that you should never skimp on... these are the things that simply can notbe changed later on easily.
So for the novice, at the very least .... (in my humble opinion)
Bottom Drains - 110mm and each with their own 110mm pipe!
If you are not going to go for a static filter (ie: Vortex, or Nexus etc) of some kind which can handle solids being pulled into it.... then you build a sump or settlement tank - which can be isolated from the pond and drained completely.
From this you can now always pump from this via 50mm if you want to run high pressure systems..... or you can continue to gravity feed to a secondary set of vortex's to biological.
If you mess up and only install a 50mm bottom drain, or you share the bottom drain lines then you will forever be stuck with a pump fed system. So do not allow the cost of 110mm piping and fittings scare you...be scared rather about the costs of emptying the pond and cutting open the floors and doing this process over if you go with the wrong system and it does not work for you.
On the Aeration Drains.... I have ponds of varying depths - some being proper ponds - ie: 1,8 and 2m deep and one being a QT Pond where it is 70cm deep - I have installed aerated bottom drains on all of them and they do not churn the waste in the water and they are crystal clear....... again this is not something you can easily install afterwards....... your airline is buried in the concrete floor of the pond...... they are very cost effective to run - I use an 80W linear diaphgram air pump - which is far cheaper than pumping water to a waterfall...... again air pumps are another topic..... rather go for linear diaphragm which are capable at producing air at depth than electromechanical or blowers. Linear are far more expensive, but cheaper to run - the equivalent in electromechanical would draw at least 900W of electricity and they would last about 1 year and then the diaphragms would be shot!
That said I am not talking anyone out of waterfalls...... koi love waterfalls! But I would never build any pond ever again without an aerated bottom drain.
Another point on the media - most koi people look at the Nitrogen cycle and they talk about Nitrosomanas and Nitro bacter... but many do not realise that there is far more that takes place in a pond and many more other "thingies" that get involved in the 'cleaning' of the water in a pond.....
Now please bear in mind I am not trying to sell anyone a Nexus here.... that is not my goal..... and there are many other local "copy" filtration systems which work in a similar principal to Nexus..... I am merely pointing out that there is far more to filtration than what we were all originally taught!
In 2006 Koi Carp Magazine printed an article called "Activated Sludge or Healthy Bio Film" - the research behind this article took 3 and a half years....
I will quote it, if anyone would like the article and pictures please email me and I will glady email you the documentation:
It was a comparison between Japanese matting with Kaldnes k1 moving bed technology, in combination with the Answer. The test set-up was three
identical ponds with the same amount of koi that were getting exactly the same amount of food every day. The biological results were quite surprising for the Kaldnes moving bed – they were actually too good to be true. The nitrate removal rate was very high compared with the Japanese matting, and this lead to many discussions because the total surface area was the same. Also, sometimes the koi needed to be treated and all the ponds were given exactly the same dose. We saw that often, the
treatment was given a biological boost by the Kaldnes moving bed. After some thorough investigation, we understood why this difference was occurring. It surprised us, but in the end it was logical.
The discussion lead us to bio film development and how to generate it. So we had to go back to the basic science of bio film generation. In diagram 1 you can see a schematic diagram build-up of a bio film. The most important layer is the organic macro molecules that act as a primer layer for the Extracellulair Polymeric Substances (EPS), or in other words, the bio film. Without the macro molecules you cannot bind the bio film to the media. In picture 2 you can see a macro molecule on Japanese matting. As you can see, there aren't many macro molecules on the surface of the Japanese matting, so we were asked ourselves, 'why this is happening?'. We used some special techniques to find out... As you can see in pictures 3 and 4, the Japanese matting is glued together to create a stable matting. We were interested to find out what kind of glue they used. To find out, we had to prepare the media for a Scanning Electronic Microscope where we could use an ESD technique to find out what the glue was made of. ESD is a materials analysing method that gives a chemical combination, by percentage, of the glue used.
In picture 5, by point A, we measured the glue and you can see the result in diagram 2 – this was interesting to us. In this diagram you can see many chlorine combinations, which are the reason why the macro molecules don't like to grow on the Japanese matting. In picture 6 you can see there is no bio film on the Japanese matting. So we analysed a piece of Japanese matting that had been treated with a lot of chemicals in a filter for many years. We used a confocale microscope where the sample is immersed in water – in this picture 7 you could see clearly that the glue was 'blown up' and would release chlorine combinations into the water. We showed the results to several microbiologists who concluded this specific Japanese matting could not hold or create a bio film, and is actually a mechanical filter that holds activated sludge as you can see in picture 8. This was quite shocking but was the correct explanation why in our test the Kaldnes moving bed was performing much better than the Japanese matting.
There was biological performance in the Japanese matting filter, but it was actually activated sludge. This means that in the waste the bacteria would do their job for us, but this could also harbour sulphate reducing bacteria (SRB) that could make our koi ill. We even suspected this could be one of the reasons why koi develop Hikku in older systems that have Japanese matting as their core filtration. However, we had to check another type of Japanese matting to find out if it was using a glue too – this was not the case as you can see in diagram 3. But there was not much bio film development there either. So, we believe that Japanese matting is a mechanical filter that holds activated sludge that will do the biological action, however, if you clean the media, you would loose much of your bacteria.
Primer Layer
As we could see in the Japanese matting, it was very difficult to get the first layer as shown in diagram 1. The first layer is organic macro molecules that act as a primer layer for bacteria to grown on. Without this it is impossible for them to attach to the bio media. This primer could be generated in just one minute or it could take longer if the surface of the media is not clean.
However, each pond's water is unique and has a different chemical balance – this could mean a long waiting time to generate this primer. So, the question was, 'how quickly we can generate the primer layer?' Some people used caustic soda to clean the K1 but the results were no better than the non-treated K1 and some dealers had high nitrite values, which you would not expect when using this method of cleaning. The other values where fine. It proved a complicated question because, although this was not common, some people also found very high pH values. So we asked dealers to use live bacteria cultures to generate a bio film more quickly. It produced some better results and the nitrite problem was reduced, but not to a level we were happy with. The only reasonable explanation was the primer was not 'working' yet and this is when we thought of using potassium permanganate to create the primer layer quickly on the bio media surface.
We encouraged people to do a blind test using potassium permanganate. In this test we used 40 gallons of tap water with 50 litres Kaldnes K1 media and one teaspoon of potassium permanganate crystals and aerated it all. And after this it was rinsed twice with clean water. Normally, it takes a few days to get K1 media to sink into clean tap water, but with this method it was taking a few hours. The same dip was performed with the Japanese matting we were using in the filter system. We did the same setup for a second test, but here we used live bacteria (Cleartech Filter Balance Pro) to help the start-up instead of using the potassium permanganate dip. The tanks used in the test were identical, holding 500 gallons of water with five koi 10in-long. The first chamber had Japanese matting and the last chamber had 50 litres of Kaldnes K1, aerated with an Airtech 40. The test results can be seen in diagrams 4 and 5, where you can see the ammonium peak in Tank 1 was not reaching higher then 0.4 mg/l. However, in Tank 2 the peak was reaching almost 1.5 mg/l on day five. The nitrite peak was starting in Tank 1 on day four – it was higher than 0.38 (maximum reading of the colorimeter) and was coming down on day 10. But in Tank 2 the peak started on day 6 and came down on day 18. This test made it clear that if the filter was started correctly, the nitrite problem was solved.
Adding the live bacteria also helped to reduce the ammonium peak. So, now the important question was, 'why was the caustic soda not creating a good primer layer?' The reason for this was quite simple, if you use it, even after cleaning, it leaves a thin film on the surface of the bio media. This thin film has a base soap effect – if you clean a microscopic slide with caustic soda, when it dries you will see a white film, which means the surface is not clean. This caustic soda residue of gives off a chemical effect that dissolves the EPS layer that the bacteria need to survive, and it also means the macro molecule film (primer) can not be developed. But potassium permanganate doesn’t have this problem as you can see in diagram 4 and 5.
Bio Fouling
When starting a new filter we want to create a bio film that is very thin in the beginning – most of the time this would be an aerobic process. However, when the bio film becomes thicker, the oxygen diffusion ability is going to be lower, therefore an anaerobic zone is generated in the bio film. Diffusion of oxygen is a very slow process and the bacteria will consume a lot of it. So, in the aerobic zone we will have nitrification and in the anaerobic zone we will get denitrifcation. But bio fouling is a biological process in the bio film because, in nature, other animals would be eaten by other living creatures and in this case, diatomeen and zoo plankton would eat bacteria, and rotifers would feed themselves again to these living creatures. Diagram 6 shows this. To prove this to you, Jan took a very special picture of the Kaldnes K1 media in situ where you can see the macro molecular film (primer) and the white spots in the water are diatomeen and plankton. This picture 11 is quite unique and demonstrates that there are a lot of living creatures in the media. In picture 12 you can see the plankton that was found in this K1 media.
EPS
If we feed our koi lots of food, we generate more waste which is the food source for the bacteria that generate EPS (Extracellulair Polymeric Substances) (i.e. bio film). If we generate more EPS we create a thicker bio film. In picture 12 you can see the intense red part that is the bacteria colonies with the transparent EPS, which is the food source for the bacteria. In picture 13 you can see a Scanning Electron Microscope image of these bacteria. If we analyse the EPS layer with an analytic REM/RMA (advanced methods for analyzing living tissue or materials) methods we can find the following elements in these substances. The most important ones are phosphorus and Kalium, which are needed to keep the EPS alive and are the food source for the bacteria. PP treatments So, after the big test with PP treatment to get a clean surface and a stable bio carrier material, we could now generate the macro molecular film (primer), needed as a sticky base for the bacteria.
However, most of us would say we use PP to kill our bacteria, not help it thrive. To prove it works we have carried out some tests on a live system where we used Japanese matting and Kaldnes K1 media. In this test, we counted the amount of bacteria in each hour of the test and the results are quite shocking! We found the Kaldnes K1 media recovered quickly after a PP treatment but it was much slower in Japanese matting. So again, we had more questions then answers... Firstly, we looked at the chemical reaction after a PP treatment and we found the end residues are actually a nutrient for the bacteria and are the same as we have found in the REM/RMA. This was the reason the filter had a boost after a PP treatment. For the Japanese matting this result was less obvious and it was taking more time to recover from the treatment. We think now that this is because of the protective surface area inside the Kaldness K1 media.
We believe what is written in many books about nitrogen conversion is not correct and that in the bio film things are happening that we did not know about a few years ago. The methods used to analyse bio films are becoming more advanced and we know now that 22 different groups of bacteria are involved in the protected bio film created in the K1. We believe protected bio films are the key for successful koi keeping as they mean less health problems for your koi.
Activated sludge is a home for SRB bacteria that could generate health problems and does not create a stable protective bio film. After three and half years of research it was now clear to us that Kaldnes K1 moving bed had much more to offer than we first thought..."
End quote...
The other really important factor is the actual design of the pond..... in every pond I have been to where there is constant niggling health problems - the design of the pond was wrong....
A favourite that some ponders did at some stage was to install many different returns to the pond, each on their own valve - some mid water, some bottom of the pond, some top of the pond etc and then on week 1 they would open say 4 of the valves and circulate the water in a clockwise direction and then the next week they would close these and open the other 4 and circulate the water in an anticlockwise direction... sounds great... except they did not take into account that every single pipe in a pond must MOVE water constantly through it.... if you leave any pipe for a short length of time without water physically moving through it the water literally goes off and the harmful bacteria is unleashed on your koi when you do open those valves! You can check this by taking a length of 50mm pipe and 2 end caps - fill it with pond water, let it sit for a day and then pour it out - the stench that will come from that water is unbelievable!
So design is critical - and if you at thevery least install the correct drains and use 110mm pipe then any system you go with can be changed fairly easily afterwards if you realise that you made the wrong choice![right]
And lastly the running cost of a pond..... I am not sure what everyone else pays for electricity - I am on a plot.... and our electricity could be different in charges.. we pay 0.504c k/Wh and this is before Eskom gets its next increase which is scheduled to be anything from 35 - 45%
So per month this is roughly the cost of running pumps - before the increases to come:
2.2KW R 798-34
1,5KW R 544-32
1.1KW R 399-17
0.75KW R 272-16
0.6KW R 217-73
0.45KW R 163-30
0.25KW R 90-72
Does not sound like much does it - but now add this up over a year....
I would rather pay R 1088-64 per year than R 4 790-04 per year...
and over 5 years R 5443-20 is still better than R 23 950-20
and may Eskom bless our poor soles with their next 3 increases!
[right]
Home 
Calendar
I am running 4 disasters the last six years..............
...and that with seven 1,1 kW pumps and one ,75kW pump, pumping water direct to the filters via 50mm pipes!
please note, no culling this time round. 
I'ts amazing and would not change a thing. 
........you are lucky indeed!