How Long Does New Pond Syndrome Last?

The time it takes for new pond syndrome to go away varies depending on the size of the pond and how long it was dry. The average is around 3 months, but it can be as short as a week or last up to 6 months.

The first sign of new pond syndrome is fish dying and a cloudy water condition caused by bacteria overgrowth. The cloudiness usually clears up in 2 weeks or less, but the dead fish will still be apparent for about 6 months because they are decomposing slowly under the mud.

Good bacteria can take up to 3 weeks to colonize pond surfaces and establish themselves in a new pond. This is why this process of establishing beneficial bacteria is necessary right after moving a fish into a new tank, or after an extended period of time without fish in it.

What is new pond syndrome?

New pond syndrome is not a disease at all, it’s actually a beneficial bacteria imbalance caused by lack of use or frequent new additions.

Poor quality water and fish, plants, or other materials added to the pond without first testing for ammonia, nitrite, and then adding healthy bacteria which has been bred to aid in breaking down harmful toxins. Anything that adds harmful toxins to a pond can cause this imbalance, be it pets, livestock feed, or even humans.

Attack of the Hammerhead Worm
Attack of the Hammerhead Worm

How does new pond syndrome happen?

A pond loses the good bacteria that live on the surfaces in its water when it becomes infested with bad bacteria (often introduced by the introduction of new fish, waterfowl, or livestock feed). Without good bacteria to break down ammonia and nitrite before they become deadly toxins, fish will die.

When this occurs in a newly constructed pond with proper testing for ammonia and nitrite levels prior to the introduction of fish it is often referred to as “New Pond Syndrome” because it usually takes place within the first month to three months of the pond’s life.

Why does it happen? 

This condition is limited to newly constructed ponds or new ponds that have not been used for a long time. A pond becomes unbalanced when it fails to have a healthy bather population (good bacteria) on its surfaces. This means lack of use for the pond, new materials have been added without testing for ammonia and nitrite first, or too many fish have been added to small a pond.

How can I tell if my pond has New Pond Syndrome?

Look at your pH (acidity) which should be between 6.7-7.6, measure the levels of ammonia and nitrites, and measure your water temperature. 

If everything is within the range you may not have this condition but your fish still may be dying due to another health issue. If all are within normal ranges, then test for the presence of good anaerobic bacteria with a pond test kit. This will tell you if your pond has “new pond syndrome” or not.

Is new pond syndrome harmful?

In most cases no, it is actually beneficial to the overall health of the water body. However in ponds that house koi or goldfish it can be very fatal.  It is encouraged to try and correct this condition before adding fish as it is possible for them to contract any diseases that the new pond may have.  

How can I fix new pond syndrome?

Test your water quality in areas where you suspect high levels of ammonia and nitrites, this will help to locate which section of your beloved new pond is creating the imbalance.

Adding clean water from another pond that is proven to be healthy will help your new pond but you must be careful not to add so much it replaces all of your current water, this could create a different imbalance if there is something already living in your water.

How long does it take for a new pond to clear up?

It can take several weeks or even months for the pond to clear up and for all of the beneficial bacteria to develop.

This is due to the changing bacteria populations that will be taking place.

The slime on the pond surface may take a while to clear up, and it may even be quite some time before you see your fish again. There are also other factors involved in this process because this time period will vary depending on many different aspects of your pond system:

  • Size of the pond (bigger ponds take longer)
  • Flow rate of your water source (more flow rates in the summer can be harmful to fish and plants)
  • Level of dissolved oxygen in the water. (low DO levels mean less beneficial bacteria)

It is also recommended that you do not feed your koi or run any filtration system until you see that the water has cleared up.

There is one good thing about new ponds: there will be no unwanted bacteria present to compete with your developed beneficial bacteria, so it should not take too long for your pond to clear up and stay clear.

When the bottom of the pond starts to clear up, your new beneficial bacteria are working.

If you have ever had a pond that cleared up quickly and then becomes cloudy again, this is most likely due to over-feeding the fish or having too much feeding going on in the pond.

You need to be careful with what goes into your pond after it has been completely cleaned up:

  1. Not over feeding the fish, even if they are begging for food
  2. Don’t throw anything into your pond that may pollute your water or feed your bacteria that you do not want such as certain mulch or fertilizer products (make sure to double-check this with the manufacturer of any product.)
  3. If you have to clean out the pond with chemicals, be sure to run a huge amount of water through it before you turn your filter back on.
  4. Don’t overstock the pond. This will help ensure that all of your fish can get enough food without creating problems to the balance in your pond ecosystem and cause more feeding which can lead to cloudy waters.
  5. If you have a new pond, avoid planting any aquatic plants in the first year or two.
  6. It is not recommended to plant any terrestrial plants in your new pond either (a few small potted ones are okay).

Why is my new pond water turning green?

This might be related to the new pond syndrome.

The key to keeping your water clear is to keep up with the necessary maintenance.

Years ago, I was told that if I ever had a problem with green water in my ponds that it would be a permanent condition. Nothing could be further from the truth. If your pond already has some green algae buildup, then there are some things that you will need to work on. Let’s discuss these issues and alleviate your concerns.

One of the first issues with green water is to determine whether you have a seasonal or permanent problem. If it has been raining for four days straight, and it is the beginning of May, then you will most likely be dealing with a green algae bloom that occurs from time to time in all ponds.

What I mean by this is organic material (leaves) has built up on the bottom and then when it rains, a combination of the leaves and scum are being washed into your pond. So if this is what you are seeing, don’t panic. All that needs to be done is siphon out all of the material from the bottom of your pond.

By doing this, you will temporarily reduce the amount of green algae present. But being the opportunist that it is, green algae will continue to grow very quickly in your pond until you figure out how to keep up with the maintenance on a regular basis.

I am sure that all of us have had this problem occur sometime or another. For me, this occurred numerous times in the last ten years. But over time, I have been able to reduce its occurrence by doing some of these things:

  • Install a good UV sterilizer in my pond and keep it covered during the fall months when I am not using it. The UV will help kill off any green algae as well as other harmful microorganisms.
  • Make sure to use a good, beneficial water clarifier. I use Pondcare pond Accu-clear pond water clarifier. They also make other products that work very well as well but it is designed for ponds that already have some green algae present in the summer months.

Some hobbyists recommend leaving your pond uncovered during the fall month so that it can “breathe”. I do not recommend doing this. The only thing your pond will be breathing in is dust and other contaminants, which will reduce water clarity.

To sum up

New ponds require time for the beneficial bacteria to develop and mature before they can support a healthy ecosystem.

Depending on your water source and the size of the pond, it can take a while to see any clear change.

There are things that you can do to help speed this process up, such as not overfeeding or adding plants early on in the life span of your new pond.

It may also be helpful to run your filter but only lightly so that not disturb the beneficial bacteria in your pond, or even remove it entirely until you have seen a change.

Good luck!