Fish Pond Bio-Filter Essentials

Did you know that us humans convert the ammonia in our bodies into urine, whereas fish simply excrete it continuously from their gills into the surrounding water?

Normally in a river or the sea it is diluted by thousands of gallons of water to render it harmless. But nobody told Mother Nature about koi-keepers and their ponds, where ammonia can build up to a dangerous level due to the large number of fish in a small volume of water.

A koi pond has to deal with two types of pollution;

• solids waste and
• dissolved waste from solids.
  

Therefore it is essential to remove the solid wastes from the water before they have a chance to dissolve.

If we can do this we gain; better water quality, fewer dissolved pollutants and ultimately less fish health problems :o)

Once the solid wastes have been collected, it is important that they are flushed out of the system regularly, before they get the chance to decompose.

In summertime this could be as often as twice a day! This means that any settlement chamber incorporated into the filter design will need to have a drain to allow easy flushing to waste.

It doesn't matter whether the solids decompose in the pond or the filter - the result is the same - polluted water!

To maintain good water quality it is essential that solids are removed from the pond and filter before they have time to pollute the water

Any trapped solids must be removed from the system on a regular basis, otherwise they will simply decompose and pollute the pond. They will also encourage high levels of opportunistic bacteria.

For good filtration and water quality very little solid waste should be allowed to enter the 'biological' section of the filter. To restate the point made previously; the more effective the settlement area of the filter at removing solid waste, the lighter the load on the following biological section - provided, of course, that trapped waste is removed before it decomposes.

This entails:-

Regular maintenance to keep the biological area clean and free of mulm,

Reducing the level of dissolved organic compounds by effective settlement/entrapment, together with regular cleaning of the settlement area.

If we can remove solids from the system before they decompose and at the same time keep the biological section of the filter fairly clean we will;

• Encourage a vigorous growth of nitrifying bacteria
• Reduce the load on the biological section
  

Do you see a repeated theme here? Cleanliness is the order of the day!