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Most Frequently Asked

How often should I change my aquarium water?

Most aquariums should be cleaned every 2 weeks on average. It is easier to combine cleaning and water changes by using a gravel siphon, as this also removes any dirt and waste from the bottom of the tank.


When can I add new fish to my tank?

If you are introducing new fish to a matured aquarium, then there shouldn’t be a problem. However, you should monitor the ammonia and nitrite level for the few days following introduction as a precaution. Also, you should quarantine any new fish for at least 4 days in a separate tank before adding to your main tank. This will help to prevent spreading any diseases.

It is advisable to run a new tank with water only for at least 1 to 2 weeks before adding fish, to allow the filter to build up some beneficial bacteria. It helps to add King British Filter Aid + during this period to help the filter to mature. Fish produce ammonia through respiration, and release it into the water through their urine and across the gills. In a matured aquarium, the filter can remove the ammonia quickly before it causes any problems. However, in a new, un-matured aquarium the ammonia will linger and may build up and cause problems. If fish are added straight away to a new tank then the ammonia they produce can poison them and they may die. Also, once you do start adding fish, they should be added slowly and gradually, not all at once. Spread it out over of a period of weeks by adding two or three fish at a time, to allow the filter to adjust to the larger load of ammonia and nitrite.

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Previous Questions

    Latest Questions: Ask the Experts & FAQs

  • When can I add new fish to my tank?
    Mature Tank If you are introducing new fish to a matured aquarium, then there shouldn’t be a problem. However, you should monitor the ammonia and nitrite level for the few days following introduction as a precaution. Also, you should quarantine any new fish for at least 4 days in a separate tank before adding to your main tank. This will help to prevent spreading any diseases. New Tank It is advisable to run a new tank with water only for at least 1 to 2 weeks before adding fish, to allow the filt…
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  • How do I calculate the volume of water in my aquarium / pond?
    Visit our help page and fill in your tank or pond dimensions in the Water Volume section
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  • One of my fish is bullying its mates. What should I do?
    Bullying can be a problem in fish tanks, but there are things you cna do to help restore harmony to your community tank. Add some plants or ornaments If you have no plants or ornaments in your aquarium, then it is a good idea to add some. These will offer shelter and hiding places for the fish that are being bullied. It also helps to separate areas of the tank.  Check that your fish are compatible You should also check that the fish in your aquarium are actually compatible. If only one fish is bein…
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  • I am going on holiday for a week, can my fish be left without food?
    This depends on what kind of fish you have. Most cold water fish will be fine for one week without food, however tropical fish usually need to be fed more often. There are a few options for keeping your fish fed while you're on holiday. You can use holiday blocks, such as King British Holiday Food Blocks or King British Weekend Feeders, which release the food slowly into the water over a period of time, or you could ask a friend or neighbour to feed your fish. If you ask someone else to take of your fish, …
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  • I think my fish has a problem with its swimbladder
    The swim bladder is a small organ inside the fish that can fill up with air or deflate, allowing the fish to move around in the water column more easily. The swim bladder is quite prone to infection, which can cause bloating, disorientated swimming, and involuntary floating or sinking. Alternatively, the gut of fish may have trapped air, caused by constipation or by an infection.  ✔  You should stop feeding for a day or two, and check the water quality using King British 6 in 1 Water Test Strips.&n…
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