Tag Archives: ammonia

Keeping Koi Ponds Healthy With Chemical Filters

Sometimes your biological or mechanical filter does not effectively clean wastes from your pond. This is when you have to resort to using what are called chemical filters. These are also sometimes called biological converters.  These are solutions or powders that are added to your pond to correct common problems such as an excess of nitrates, an excess of ammonia,

Every koi pond owner should invest in a ten dollar nitrate test.  This test should be done at least once a month but ideally once a week. A simple test at the right time may prevent a small problem from becoming a catastrophe.

 

You can buy all kinds of tests to monitor the water quality in your pond including:

 

  • PH balance
  • Ammonia
  • Nitrate
  • Alkalinity
  • Salinity
  • Chlorine

 

 

Do not confuse the terms water quality and water clarity. Crystal clear water can contain compounds that are deadly to your fish. Green water, caused by excessive phyto plankton growth can actually be beneficial to the fish although not very beneficial to the pond keeper who can’t see them. Water clarity can give some indications as to mechanical filtration effectiveness but it does not necessarily tell you what is happening with the chemical make up of the water.

 

A pond with a biologic converter and filled with Koi is a rather complex, and delicate eco-system. Each component of this system requires the other components to perform its job. Fish waste and bacteria and fungi to ammonia compounds convert other organic waste. These compounds can be toxic to the fish, which then can die a very visible, hard-to-watch death.

 

However, if your koi pond has a healthy biologic converter it should be populated with mitrosomonas bacteria. This is the type of bacteria that greedily consumes ammonia and converts them to nitrites. Unfortunately, the nitrates are just as toxic to the fish as the ammonia. Again, the biologic converter comes into play with a population of mitrobacter bacteria that convert the nitrites to nitrates. The nitrates are basically inert to the fish but usable by plants and algae within the pond. As the plants and algae grow and the Koi eat them, the cycle of self-cleaning starts all over again.

 

Nitrosomonas and nitrobacter bacteria are aerobic bacteria that require oxygen to convert their “food” to energy just like the fish. This is why an ammonia or nitrite filled pond can smother both and leave you with a lifeless swamp.

 

Biological Filters That Can Keep Pond Fish Healthy

You don’t have to pour a bunch of chemicals into your koi pond to keep it free from bacteria. A biological filter is a medium of some kind that at converts harmful nitrogen by products from aquatic animals into less harmful nitrates. This type of bacterial occurs naturally in nature’s lakes and streams. It usually attaches itself to rocks or stones.

 

These bacteria are already noticeable on the walls of most koi ponds. They also can be found on the inside walls of the pond plumbing, attached to the skimmer basket, and on the rocks that form a waterfall. The reason we build biological filter systems is to increase the available surface area for these bacteria to colonize. It is simply not enough to dump a plastic liner into the ground and surround it with dirt. Rocks help grow the bacteria that eat nitrates that are harmful to koi.

 

In an effective koi filter, two, three or four chambers of suitable media, on which our nitrifying bacteria can grow and thrive, normally represent the biological stages. These chambers can be any shape. They should also be benched steeply towards a central drain valve in the base of the chamber, so that any solids that do collect in the chambers can be easily be removed by you.  If you own a biological pond filter it is important to unclog it to maintain superior water quality.

 

This green stuff that grows on biological filter mediums is called a biomasse. Bimoasses of friendly bacteria need both an adequate supply of ammonia oxygen and nitrite to survive. Again if the mechanical stages of your filter are not working effectively, the biological media will gradually become clogged with debris and your good bacteria will die.

 

In order to ensure the biomass has an adequate supply of oxygen, air should always be pumped into the filter, by placing air stones under the media, on the filter grids and air introduced by way of an air pump. Without an air pump, a biological filter will never perform biologically as it should.

 

There a wide range of medias to use in the biofilter. Gravel is the most popular choice but synthetic medias are also a good choice.

 

Synthetic medias don’t have a lot of the problems that gravel does. Being lightweight and less clogging makes synthetic medias easier to handle and clean. Most of the synthetics have a large surface area per cubic foot for growing bacteria. This attribute gives a bigger biofilter in a smaller space. However synthetic medias may not grow the “algae lysing” type of bacteria that naturalizes very easily in genuine pools and steams. The “algae lysing” bacteria grow better in slightly stagnant and low oxygen zones created by a rock, gravel or stone based filtration media.