Getting Started

My water quality experiment has been running for a week now but there's very little visible change. This is not surprising considering it was started as a sterile environment with raw tap water and the only things added have been dechlorinator and three Saki Hikari pellets. This is what many koi keepers go through when filling their ponds for the first time and is often referred to as getting the pond to cycle. This means establishing a colony of bacteria in the filter which break down the waste products that build up into safer compounds, ammonia being the most harmful to koi. The cycle part refers to the nitrogen cycle, of which ammonia as a compound of nitrogen is part of.

A koi pond filter can take anywhere between a week to over a month to fully cycle depending on the conditions. Around 20 days is about average to establish a working bio filter but it may take many more months before it's at full strength and mature. This is why new ponds can experience problems often called new pond syndrome when too many koi are added too early. Nearly any body of water will not remain sterile for long and even chlorinated tap water will not kill all organisms, the reason you shouldn't clean contact lenses in it, but there are ways to speed things up.

The quickest way to seed a bio filter is to introduce some media from an already established filter. For most people this isn't an option and it could be a source of introducing disease so the next best thing is to buy a product that contains a ready culture of bacteria. These can be great to get things going or as a boost but they don't contain the true nitrifying bacteria needed for an efficient and stable koi pond filter. The nitrifying bacteria Nitrosomonas and Nitrobacter (Nitrospira is in fact more common as the nitrite reducing bacteria in water) are much slower developing and being autotrophic need a steady supply of the chemicals ammonia and nitrite to feed on, so are very difficult to store alive. Until these bacteria gain in numbers it's best to carry out regular water changes and only introduce a few koi with light feeding to start with.

In my experiment I've not added any bacterial products as I wanted to let things develop naturally and not be influenced by an abundance of certain strains. Most of these products contain heterotrophic bacteria which can feed on a variety of things and are responsible for mineralising organic waste into ammonia. They can do some of the work for the nitrifying bacteria but given a choice they prefer organic waste because it releases more energy.

Without any koi the only source of ammonia so far will be from the food pellets but these first have to be mineralised by hetertrophic bacteria. Having tested the water the ammonia levels are registering at around 0.15 mg/l which in a pond of koi would not be healthy but it does suggests that bacteria are present. One of the sources of the bacteria could have been in the koi food itself as Saki Hikari contains a probiotic to aid digestion. I'm going to switch foods to see if this makes any difference but it maybe something worth investigating later on.

Koi Water Treatment Experiment

Back in August I wrote about a new water treatment for koi ponds called Aqualibrium, which while I believed it could be effective in removing algae I was also sceptical about some of its other claims. Well the nice people from Aqualibrium contacted me and along with some more information sent me a bottle to try. I must say going on the first impressions, the aluminum bottle looks good but what I and many other koi keepers really want to know is does it work?

Now never one to turn down a free gift I was interested to give it a go, but the primary reason someone would buy this product in my opinion would be to get rid of algae and blanket weed, neither of which is a problem for my pond. This time of the year is not really ideal for trying a koi pond treatment as the temperatures are going down and with daylight hours getting shorter most algae will tend to die back by itself anyway. Having tested all the parameters of my pond water I realised that any improvements in quality would be difficult to detect without expensive and very sensitive equipment. The problem then is how do you test an algae treatment when you haven't got any algae? To be fair to Aqualibrium and in the hope of getting some dramatic results I've decided upon setting up an indoor test rig that will be more controllable.

Using a large vase of water I hope to recreate in miniature the conditions found in some koi ponds, starting by growing algae which shouldn't be too hard. With most of the organisms present except for the koi it will be possible to pollute the water beyond a point that would normally be tolerated. Before I start this experiment I have to say that I'm not a scientist and there may be a few flaws in my plans so even if the results are conclusive this shouldn't be taken as definitive proof. Really this is just a bit of fun and although I have a few theories I'm not totally sure what's going to happen.

Starting from scratch with fresh tap water and new filter media I shall go through the process of establishing a bio-filter which often causes problems for many beginners when setting up a koi pond for the first time. As Aqualibrium works by activating the microbes already present in a pond we need to first establish a healthy culture of the right bacteria. One of the main reasons that a pond turns green is because of the build up of nitrate levels produced from the nitrifying bacteria. By including a small filter in the vase that supplies an abundance of nitrates and given plenty of day light, algae should easily grow. I'll try to explain the processes involved in more detail later on.



I'm using a small aquarium filter that I replaced the foam with Fluval Biomax - a highly porous ceramic media, because this media provides a very large surface area for bacteria to grow on while it shouldn't trap the algae as it develops. By regularly feeding the system with koi pellets and testing the water I should be able to monitor any changes. Starting with chalky London tap water with a pH of 7.5 there are as one would suspect few impurities worth testing for but it's worth mentioning that nitrate levels are between 25-50 mg/l. This is perfectly fine for koi but it does show that when doing water changes you may not be reducing the nitrate concentration in your pond as much as you think. In fact in some ponds the addition of more nutrients in fresh tap water can be the cause of algal blooms.


To avoid this possibly becoming like watching paint dry I will update when anything significant happens. As well as a test of Aqualibrium this will also be a good opportunity to explain and try out certain theories of how a koi pond filter works and how you can improve yours.