Fish Ponds

After getting a pond established people often find that fish suddenly start dying for no apparent reason. Various medicines are added with no benefit and the fish continue dying. Another cause should be looked for other than disease and this could well be poisoning. There are many innocent ways to add harmful chemicals to your pond. Often a freshly installed concrete waterfall is to blame, or a newly slabbed area adjacent to the pond. This is because the water that has run over the new cement and into the pond will have leached some lime from the cement. In a large pool this isn’t so much of a problem, but in the average back garden pond it is often fatal. Lime will alter the PH value of the water making it deadly for the fish. It is also a problem that will not go away so the best way to cure it is to treat all new cement work with a neutralizing agent, carefully following the manufacturers instructions, or paint the cement with a special pool paint to cover it.

Garden sprays used on nearby bushes can be just as deadly as the spray may drift onto the water. Lawn fertilizer must also be used carefully as the run off water from a lawn can be poisonous. If any nearby fences are to be creosoted then great care must be taken not to splash the creosote into the pond. Any foreign chemicals in the pond should be avoided at all costs because fish do not have the same ability to remove poisons from their bodies the way that most animals do.

Even things that wouldn’t harm us such as copper pipes should be avoided as the chemicals in such an enclosed system as a pond can build up in the fishes body until it becomes fatal.

Both copper and lead pipes are often used in stone fountains which shouldn’t be a problem, but no more such piping should be used and plastic, or rubber should be used as an alternative for long runs. Even plastic can be harmful to fish as a lot of cheap plastics contain cyanide compounds that can leech out. This is why plastic filter materials and plastic hosepipes should be of a good quality and specially made for the job. Some cheap butyl pool liners can even be harmful as they can contain too much butyl that in itself is poisonous in small pools.

Another very common problem is autumn leaves that fall on to the pond and sink to the bottom. There they will rot and if not removed before the winter, will produce a high concentration of poisonous gases dissolved in the water. If ice forms the gases will not be able to escape and will build up to toxic levels. Conifer needles are especially harmful as they will change the PH value of the water making it acidic as well as rotting.

A relatively new problem that is starting to emerge is that caused by the incorrect use of UV steralizers. If they are not used in conjunction with a biological, or chemical filter the ammonia levels can build up in the pool to toxic levels. The pond may stay clear but be very poisonous to fish so don’t think that a clear pond is automatically a healthy pond because the reverse is very often true. Indeed there is some evidence to suggest that a slightly green pond is healthier. The reason for this is that there is a vitamin in the algae that causes green water that is therapeutic for the fish.

One problem that can only be put down to carelessness is the incorrect use of medicines. Incorrect dosage is a big problem as people often think that, if a little is good for the fish, a lot must be better.

Mixing of chemicals can lead to problems with them interacting to produce a poisonous product. Whenever using chemicals in the pond the manufacturers instructions should always be followed carefully and to the letter. Always leave at least a couple of weeks between using different chemicals and a month would be better. Some chemicals remain in the water for even longer so do read the bottles.

The use of salt can be a problem, Table salt is poisonous and should never be used, but sea salt, rock salt, or a branded pond salt is a very good tonic in small doses. Always remember that until you change the pond water the salt will remain in it. Don’t keep adding more and more every few weeks, or months because it doesn’t go away and eventually it will build up to levels where it will kill your fish.

When changing pond water remember that tap water has chlorine and often fluorine in it. These chemicals are both harmful to fish as they burn the delicate gill membranes. To a healthy fish a partial water change once, or twice a year, or an annual clean out shouldn’t hurt. If you are doing regular water changes then steps should be taken to neutralize the chlorine. There is a chemical that all aquatic retailers sell which does an admirable job of this and it also removes the dissolved metals such as copper, lead and zinc.

The simple rule is to keep all foreign chemicals out of your pond and remember that most metals are poisonous. Above all use medicines very carefully and keep your pond clean. If you do these things you won’t poison your fish.

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