You just built your pond, now what?
Tap water contains chlorine and maybe even chloramines. Filling your pond use dechlorinated or even better filtered water. These RV filters (available at Wal-Mart) really work well and are very inexpensive and they fit onto the garden hose. Well water is not better, it is usually high in nutrients and heavy metals and should be treated as well before it is suitable for plants and animal live. If there is no chloramines in your tap water, chlorine will evaporate in 48 hour. After that you can add plants.

There are four different plant categories for a pond. Submerged plants, they are the work horses in the pond. They oxygenate and filter the water, they give hiding places to pond critters, they provide food and spawning places for fish. Than there are plants with floating leaves, they will provide shade and hiding places. Than there are bog or marginal plants. These plants will frame the water garden and take out some of the nutrients as well. Finally floating plants, these plants do not need to be planted just set into the pond. They are very good in taking excess nutrients out the water. Give the pond at least two weeks before introducing fish to the pond and do not fill it to the limits. Start slowly, adding over time. Keep in mind fish do grow and they do breed.

The Nitrogen Cycle
Most common water problems are caused by having to many fish and feeding fish to much. Fish waste and decaying plant matter produces ammonia. Ammonia is also present in tap water. Ammonia is toxic and even fatal to fish. It affects their gills and takes away the slime coat on their bodies. The nitrifying bacteria present in the biological filter and in the moss which will grow on your liner converts ammonia into nitrites which are also toxic to fish. Another kind of bacteria than converts nitrites into nitrates, which than can be used as food for plant growth. It will take time to achieve a balance between plant and animal live. For starters use these stocking formulas: Two bunches of submerged plants per square yard of pond surface. One medium to large water lily for each square yard of surface area or enough floating plants to at least cover 60 to 70 % of the water surface. No more than one goldfish for 30 gallons and one Koi needs 125 gallons. A Koi pond should not be smaller than 1000 gallons.

Maintaining high levels of oxygen in your pond will keep everything in balance. Keep in mind algae likes to grow in stagnant water and so do all kinds of fish diseases and Mosquitoes. In our desert summers, pond water gets very warm and oxygen levels get very low. If you have a waterfall or fountain, the pump should be never turned off. It is good to have an oxygenator kit going, a simple air pump and air stone will work wonders. Our water is very alkaline. Our tap water is 7,5 ph but the well water can be up to 9 ph. Goldfish and Koi like alkaline water and a safe range for them is 6.5 to 7.5. The fish will adapt to higher ph, adjusting ph is very difficult and stressful to fish that is why it is best left alone.

The good bacteria we are welcoming into our ponds is aerobic, that means it needs oxygen to survive. There also is an anaerobic bacteria which sometimes develops in oxygen depleted organic matter and when disturbed can let out a very dangerous gas, hydrogen sulfide, reconiced by the rotten egg smell. This gas is very toxic to all pond life. In a natural body of water there always is fresh water coming in somehow. In a man made pond water is recirculated. We have to imitate the natural pond with giving water exchanges. Just to fill up what has evaporated is not enough. Keep in mind only the water evaporates, the toxins stay behind and eventually built up. From time to time a water exchange is a must. More frequently in the warm summer month. Take out 10 to 20 %, use the water to water your landscape and refill with filtered or dechlorinated water.