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Cloudy Water in Fish Tank - Causes & Solutions

Cloudy water is a common but frustrating problem among fish owners. Not only does it obscure your view of your beloved pets, it also doesn’t look very attractive, which is particularly annoying if you’ve spent time and money on making your fish tank a real feature with colourful gravel and ornaments. 

In this post, we explain the most common causes of cloudy water in fish tanks, and run through some simple solutions to help you get your aquarium looking spick and span once again. 

Causes of cloudy water in a fish tank

A new fish tank

Cloudy water is one of the most common complaints among new aquarium owners. Whilst it’s natural to worry about harm coming to your fish, cloudy water will not impact the health of your tank’s inhabitants. 

Often, water in a brand new aquarium will be crystal clear for the first few days, then suddenly turn ‘milky’, leading the owner to believe something has gone wrong. This is totally normal. 

A brand new tank contains little to no bacteria. Once you begin to add life forms, a number of microscopic organisms all try to establish themselves. These then begin to multiply as they feed on the minerals and nutrients in the water, which is what causes the cloudiness. The problem can be exacerbated by adding too many fish at once or overfeeding, as you are providing the microbes additional food sources. This is often referred to as a bacterial bloom, and will usually clear up on its own within a few days.

New gravel

Adding new gravel to a fish tank can create residue and tiny, dust-like specks which cause the water to become cloudy after just a few hours. Gravel residue creates a white or greyish coloured water. Ensure you wash new gravel thoroughly and rinse well before depositing into your tank.

Dissolved Constituents

Another cause of cloudy water in a new fish tank is dissolved constituents. This means that a high level of heavy metals, phosphates or silicates have dissolved into the tank water. Water conditioners, such as Tetra AquaSafe, can be used to treat this issue and get your aquarium water looking crystal clear once again. 

Causes of green water in a fish tank

There is generally only one cause of green water in a fish tank: algae. While algae is a natural part of owning an aquarium, it can look rather unsightly, and if allowed to grow out of control can become harmful to fish. But how does it form in the first place, and what can we do about it?

Excess light

Too much light allows algae to grow. It’s therefore advisable to place your fish tank away from direct sunlight. You should also be careful not to leave the lights on for too long. Taking these precautions should stop algae growth in future.

Decaying fish food

Any uneaten fish food which is left to rot in the tank leads to excess phosphates in the water, and phosphates fuel algae growth. Not only is overfeeding bad for the health of your fish, but food left uneaten can wreak havoc within their environment, too. 

Tap water

While phosphates can be caused by decaying matter, they can also occur naturally in tap water. We recommend testing tap water using one of our water quality test kits before letting it enter your fish tank - this way you can see the condition of your water before it’s too late. If you find that your tap water contains a high level of phosphate, you can either use a phosphate remover to treat it or use RO water instead.

Fish waste

Fish waste is an unavoidable part of keeping a fish tank. Nitrates are a byproduct of this waste, and naturally rise over time. If you’ve never had a problem with green fish tank water in the past, then this might be the cause. The only solutions are to clean your tank on a regular basis and keep the filter clean. 

How to stop cloudy water in a fish tank

Whilst the solution to a cloudy water problem often depends on the specific cause, there are a few things aquarium owners can do to help prevent fish tank water becoming cloudy in the first place.

1. Don’t overfeed your fish

Too much food floating around your tank will begin to decay, which leads to the growth of algae, turning tank water green. Make sure you know how much food your fish need to avoid overfeeding. 

2. Clean the tank regularly

This may seem obvious, but ensuring the tank is cleaned regularly will help to keep on top of cloudy water. Most tanks should be cleaned once every two weeks, but the number of fish you have can determine exactly how often your aquarium will need to be cleaned. When cleaning, you should siphon any debris and leftover food from the gravel which will help to prevent the growth of algae. 

3. Don’t overstock your tank

More fish means more debris. Fish like clean water, and it’s much harder to maintain a clean tank with too many fish, which leads to cloudy water through the growth of algae and other bacteria. Make sure you check the specifications of your tank or get in touch with a member of our team if you’re unsure how many fish you can keep inside it.

4. Perform regular partial water changes

You may be tempted to change the water completely when it turns cloudy, but this will only make the problem worse as you are introducing new bacteria to the mix. Performing partial water changes monthly, in which you replace approx 25% of the water in the tank, is enough to keep your aquarium fresh and clean. However - if you are experiencing cloudiness due to the tank being new, you should refrain from water changes altogether until things settle naturally.

5. Seed the aquarium

If you have access to another healthy fish tank, you can seed your own aquarium by adding handfuls of gravel from the already well-established tank to your own. This will seed the good bacteria that your new tank needs and will help to speed up the clearing of that cloudy, white water.

6. Add activated carbon media to the filter

Adding activated carbon media to your aquarium’s filter is a simple solution that will help to absorb those nutrients that fuel bacteria growth in your tank, thus helping to reduce the chances of water turning cloudy. At Aquacadabra we stock a wide range of aquarium filter media to fit filters of various types and sizes.

7. Use a clarifier

Another great solution to many types of cloudy water is using a treatment such as Seachem Clarity, which is safe for fresh and marine water, and helps flocculate (clump together) particles causing cloudy water so that they can be caught in your filter, thereby clearing your aquarium water!

Cloudy aquarium water solutions at Aquacadabra

Whether you’re looking for a bigger fish tank, water treatments or filter media, we have all of the tools and equipment you need to keep your aquarium looking great, and most importantly, your fish happy and healthy. 

For more tips and tricks on keeping fish, take a look at our blog, where you’ll find plenty of helpful guides, such as how to choose the right aquarium for you and how to clean your fish tank in eight simple steps.