Water Quality Basics in Fish and Koi Ponds

3/12/69 Water Quality Basics by Werner rev 04/08

Overview

The prolonged drought in parts of the U.S. and other parts of the world, has made us look for alternate sources of water purification. Because of the low aquifer water volume, quite a few of the wells have shown inordinate amounts of Ammonia, pesticides and a plethora of contaminants that are concentrated more than ever before.
Even our treated (City) water is showing positive readings of Ammonia, Nitrites and Nitrates. God knows what other contaminants are finding our way into our drinking water. I will try not to bore you with a lot of chemical mumbo-jumbo the information listed below will help you in your Koi and Pond keeping hobby.

What's in my water

Tap or city water is basically chemically treated water that is devoid of life. Chlorine and/or Chloramines have been used to kill all Bacteria. Since both are a deadly poisons, the water must be treated for fish use with a de-chlorinator such as Tetra Aqua-Safe (TM), Amquel (TM) or sodium thiosulfate. If you are adding even small amounts of water, a de-chlorinator should be used, since chlorine and chloramines will eat into the fish gills and reduce their oxygen absorption capacities. Tap water will still contain various minerals, heavy metals, ammonia etc., depending on your location and aquifer status, and should therefore be tested on a monthly basis with a reliable test kit.

What Water is Safe?

Bottled, Distilled, R.O. and D.I. water, albeit expensive, could be used to "top off" a pond, but should not be used used to fill a pond initially, as none of the necessary minerals to sustain life are present.

Well water, from your property, has usually had no treatment, but suffers from very low oxygen content, and depending on the locality, can contain, heavy metals, fertilizer runoff, ammonia, nitrites and nitrates, which are harmful to your fish. Testing, again, can alert you to some of these problems and some of the solutions to these problems are posted in the Zeolite and Activated Carbon sections. You can solve some of the low oxygen problem with well water and some of the Chlorine but not the Chloramine problem by purchasing a soaker wand from your local hardware supplier, propping it up on the side of the pond and spraying the water in until full. Water will absorb oxygen, blow off carbon dioxide and small amounts of Chlorine if used to fill a pond in this manner.