Setting up a new pond from scratch can often lead to a moment of disappointment as your freshly built garden oasis turns to a nasty green sludge during the first few weeks and months.

Known as ‘New Pond Syndrome’, this happens due to a chemical imbalance in your pond water that your fledgling filter isn’t yet mature enough to deal with. Don’t worry, these things settle down, and there are a few things you can do to help sort it out.

What causes New Pond Syndrome?

The simple fact of the matter is, ponds take time and effort to mature. Although you may have gone through the essentials of treating your water for chlorine before adding it to your pond, and buying an adequate pond filtration system for your setup, there are many factors that take time to balance out your water chemistry.

Perhaps most importantly is the nitrogen cycle in your pond. You water will likely look fine until you add fish to the pond, and that’s where problems begin. Fish, like every other natural create, produce waste which features a high quantity of ammonia. Ammonia is like poison for fish, inhibiting them from breathing properly and burning their scales if the concentration gets too high.

In a mature pond, the biological component of your filter will feature a huge colony of beneficial nitrifying bacteria, which breaks down ammonia into less harmful nitrites, and then into nitrates which become food for your aquatic pond plants, which then create oxygen for your fish to breathe.

This completes the cycle, but in a new pond, your colony of bacteria and your plants are not well established, meaning that ammonia and nitrites build up without turning into nitrates fast enough, poisoning your fish, potentially leading to death. This broken cycle can also effect your water’s pH level.

Stopping, preventing and curing New Pond Syndrome

There are a number of things you can do to help your pond reach maturity faster, and the first thing is to establish exactly what is going on in your pond water using pond test kits, which can check for ammonia, nitrates and nitrites as well as pH levels, well before any symptoms develop.

Once you know what is going on, you can takes steps to resolve the situation, and that usually starts with your filter:

You can give your filter a big kick start by ensuring that you have the best biological media installed, as well as helping it along with filter starting treatments, which can be bought as one-offs to get things rolling.

Ensuring you have plenty of nitrate feeding plants is a big help too, completing the cycle and oxygenising your water, but one of the biggest things you can do it DON’T OVERSTOCK YOUR POND!

While in terms of pond volume to fish stock ratio, you might well be able to fit 10 or so fish in your pond, but to avoid overloading your filter with more ammonia than it can handle, add them gradually, maybe two at a time over a period of months to allow your filter to compensate for the extra workload.

Finally, you need to clear up the mess that New Pond Syndrome has caused, which usually comes in the form of a big algae bloom. There are a range of great algae treatments available on the market that can handle anything from small ponds to lakes, and you can always add a UV Clarifier to your filtration system, helping to fuse together free floating algae particles to remove that nasty green tinge from your water.

Summing up

  • Be patient when adding fish to your pond – don’t add more than your filter can handle
  • Use filter start supplements to develop good colonies of nitrifying bacteria to your pond.
  • Ensure you have great filter media with a large surface area
  • Test your pond regularly for ammonia, nitrites and your pH level
  • Use algae cures and consider a UV clarifier.