There’s nothing worse than having a lovely pond with beautiful fish only to not be able to enjoy them because the pond water is cloudy.

And that’s the topic of the day. Why does pond water go cloudy and what can you do about it?

It’s an issue pond owners have had to tackle since time immemorial. Fortunately, mitigation and cure are relatively simple and inexpensive.

Two words we don’t hear enough when it comes to ponds!

Why does pond water go cloudy?

Cloudiness is one of the more common pond water problems but also one of the easiest to tackle.

But why does the pond water go cloudy?

Cloudy pond water is usually fish waste suspended in the water. It’s the natural process of life but a pond doesn’t usually have the natural filtering processes a river or the sea would have.

So, we have to improvise.

There are other causes of cloudy pond water, although they are less common:

New pond water – If you have just built your pond or refilled it, the water may not yet have reached biological equilibrium. This is when all the organisms and plants in your pond have reached a natural balance to keep the pond looking healthy.

The pond filter isn’t working – If you have a pond filter, it may not be working, the filter may have worn out or be clogged up.

Oxygenating plants aren’t performing – If you have oxygenating plants in your pond, they aren’t performing well enough or there aren’t enough of them. Either way, if you have introduced plants to your pond to help filter the water, they aren’t working as advertised.

Dead algae – Dead algae has been known to turn pond water cloudy. If the filter isn’t cleaning the water enough, this could be the reason.

Excess food in the water – If you’re overfeeding your fish and they aren’t eating it all, it can break down and cause cloudy water. You will often see small lumps in the water where larger food pellets are still breaking down.

As you can see, there are many causes of cloudy pond water. It’s up to you, and a process of elimination, to assess which is the likely cause for yours.

If the water looks to be impacting the health of your fish, use a liquid test kit or test strip to test the quality of the water, just in case.

How to clean cloudy pond water

There are several steps you can take to clean cloudy pond water. Which you perform depends on your pond and what’s going on.

Steps include:

Clearing debris and pond sludge

As we’re in pond maintenance mode, we may as well clear out as much debris and sludge from the pond as possible. It’s unlikely to be causing cloudy water but that debris may be preventing your filter from working properly.

Clear as much from the pond floor as possible, check any rocks or ornaments for sludge and make sure the pond filter is unobstructed.

If you have a pond vacuum, remove the fish and use it to clear as much from the pond as possible.

Check your pond filter

Next, check your pond filter. Make sure you can feel or hear the motor in the pump, then turn it off. Remove it from the water and give it a thorough clean.

Remove any dirt and debris from the unit, make sure the filter itself is in good condition, not blocked and has a clear path for water to flow through.

Change the mechanical filter and/or refresh the biological filter as appropriate.

If your cloudy pond water has a green tinge to it, consider adding a clarifier to the filter to remove more algae.

Check the health of your plants

If you have oxygenating plants, check to make sure they are in good health and alive. If the pond is new, it will take a while for them to begin filtering the water.

If they are well established, check their health and consider adding more plants if you have the space.

Check the amount of food you’re feeding your fish

There is an old rule used for fish feeding. Feed the fish as much as they can eat in 3 minutes and no more.

Check to make sure you’re not overfeeding your fish and adjust the amounts if you are. While not a common cause of cloudy pond water, it does happen.

Avoid topping up with tap water

If you have a leaky pond liner, try to avoid topping up with tap water wherever possible. Tap water contains phosphate and chlorine that can interfere with existing water in the pond.

Wherever possible, capture rainwater in a water butt or paddling pool to use as a top up.

If you have to use tap water, give it a while to find its balance before adding more.

There are chemicals and treatments available to clear cloudy pond water but they tend to fix the effect and not the cause. 

If you don’t tackle the cause of cloudy water, it will simply return and you’ll have to do it all over again.

All the steps within this post help tackle both!