How to Improve the Biological Activity in Your Koi Pond...

Biofilter performance is key to successful Koi keeping.

Biofilters are your Koi's best friend.

Better bio filter performance is application of scientific theory and common sense thinking. Good engineering principles also help as is a logical thought pattern.

All too often Koi pond filtration systems are underspecified right at the beginning when the Koi in the pond are still small. In my articles for the Pond Professor, article 2 deals with the meaningless measurement so often quoted on black box biofilters - "This product will treat pond water upto a volume of 5 000l".

This is a completely meaningless statement. I don't care if you have a hundred of these boxes connected to your Koi pond you will never know the capacity for biofiltration that these boxes deliver.

Koi keeping is not about guesswork. Start guessing and Koi start dying. It's as simple as that.

Improving bio filter performance is about ensuring that your nitrifying bacterial colonies are of sufficient size and quality to be able to completely remove all ammonia and nitrites as fast as possible out of your Koi pond. In other words an ammonia rich feed going into your biofilter must have as close to a zero reading of ammonia and nitrites as it leaves the biofilter as possible. Of course the only acceptable parameter is zero on both these counts.

The only meaningful measurement is one in which actual performance is measured and stated in a common sense fashion. For instance, SuperActiFlo moving bed biomedia WILL remove approximately 600 grams of ammonia in 24 hours per 1 000 litres of media in a dynamic moving bed system. It will also removes 700 grams of nitrate per 1 000 litres of media every 24 hours.

These are measurable and provable numbers. But even in the case of active bed media, there are assumptions that have been made. For instance, we know that the nitrifying bacteria's performance is affected by water temperature and the concentration of ammonia present in the water. These parameters are not listed which means that we have to assume that a sensible temperature of say 20C and an ammonia concentration of that approximating Koi pond conditions.

The active bed media gives us more useful information by calculating performance based on Koi food. So we get the fact that 50l of active bed media in a chaotic bubbling moving bed will be able to process a total of 250 grams of high quality Koi food per day. And in fact this figure is conservative for Koi keeping - in other water quality maintenance applications this figure is in fact doubled.

This is information that is demonstrably useful. Now we can measure performance based on quantities of food being fed to the Koi. And this performance is scientifically verifiable.

This is critically important. A standard black box biofilter cannot offer this information - if it could it would display it with extreme prominence on the side of the box! At best, a statement like "This product will treat pond water upto a volume of 5 000l" is grossly misleading.

So now that we understand WHAT to measure, we can start to think of improving bio filter performance. Got a sand filter? Chuck the sand out and fill it with Alfagrog, or better yet, Active bed media. Both will offer you a far superior biological filtration capacity than any sand medium. Yes, you need to still have a mechanical filter but at least now your sand filter will be making a positive contribution to your Koi pond water quality.

Changing your bio filter medium is one way of improving performance. Switching to a moving bed of active media will radically improve performance!

You can also improve bio filter performance by adding another bio filter to your existing one. This is usually about the only option for Koi pond keepers that didn't make provision for the growth of their Koi and it can be horrendously expensive to do it properly. It can quite often be cheaper to replace the entire system with a new mechanical and active bed system, and certainly from a maintenance point of view your Koi keeping life will never be the same again.

Bio filtration is the single most important building block in keeping Koi. Over engineered filtration more closely resembles what Koi are used to in Nature and will more accurately allow you control of vital water quality parameters that keep Koi happy, healthy and long lived. Never, ever underestimate it!