How to Clean a Goldfish Tank

Need to clean a fish tank? Grab a chair and read this to get the best information possible. Here we go!


  1. Image titled Clean a Goldfish Tank Step 1
    Every week you will need to change about 25% (perhaps more depending on your water readings/types of fish you have) of the water in your tank.
    • How much and how often depends on the weekly test results and isn't covered in this article. This article is to give new keepers a guide on how to perform a water change in the most effective, least stressful manner. Less stressful for both the fish and the keeper that is.
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    Make sure you have some basic equipment. First of all you'll need water containers of enough capacity to hold all the water you are taking out of your tank and all the water you will be replacing it with. You'll need some dechlorinator that removes chlorine, chloramines and dangerous heavy metals from the tap water. Finally, you'll need a Gravel Vacuum.
    • All of this equipment should be available from your local fish store. For water containers though you may find that a DIY or camping store is cheaper. Make sure the container is 'food grade' though.
  3. Image titled Clean a Goldfish Tank Step 3
    Prepare the clean water that needs to go into the tank at the end. To do this fill your 'clean' container with water from the cold tap and bring it up to the same temperature as the tank by either using boiled water or by adding a spare tank heater. Those with combi boilers can use hot water straight from the tap.
  4. Image titled Clean a Goldfish Tank Step 4
    Add the dechlorinator to the fresh water, stir it in and leave it to stand while you prepare the area (see step 3). If you plan to add medications, plant food, salts or other additives to the tank this should be added to the new water now.
  5. Image titled Clean a Goldfish Tank Step 5
    Don't overdo it. You're going to be walking around with heavy containers full of water. 1 liter (0.3 US gal) of water weighs 1kg so make sure they're not too heavy for you if necessary use multiple smaller containers. Also lay some towels down around the tank as its guaranteed there will be some drips and splashes. Leave the fresh water out the way for now but make sure all the empty containers that you will need are to hand.
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    If you are going to have to walk across a tiled or laminated surface consider investing in a rubber anti-slip mat. Put some slippers or shoes on to protect your feet and keep them dry.
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    Before you remove the old water, test your water for ammonia, nitrites, nitrate and PH. Wipe the inside panes of the tank to remove algae. A green kitchen scrubber (new and kept back for fish only) works, as do magnetic cleaners. Go easy, you don't want to scratch the glass.
  8. Image titled Clean a Goldfish Tank Step 8
    Use a gravel vacuum to siphon water from the gravel of your tank. At the same time this collects all the solid waste that collects at the bottom. Siphon the water into the spare buckets or containers that you prepared earlier. For gravel just dig the end of the gravel vac in about 1 centimeter (0.4 in) and watch the dirt get sucked up then move the vac over a little and repeat. For sand it's a little trickier, wave the nozzle over the sand creating a small underwater dust devil. The dense sand will generally separate from the relatively light solid wastes.
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    Check your dirty water containers carefully to ensure that you haven't accidentally siphoned up a fish provided they're all clear you can empty them out in the garden - tank water is great plant food.
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    Pour the new water in very slowly so as not to disturb, frighten or shock the fish or the gravel and d├ęcor. You might have to decant the water into smaller containers so that it's easier to lift up to the tank and pour.
  11. Image titled Clean a Goldfish Tank Intro


  • Make sure to be gentle as you don't want to harm your little friend.
  • Always have a bucket and water conditioner at hand.
  • To make sure your fish enjoys his time, change the setup of his decorations.
  • When you add water, pour slowly so you don't stress your fish of mess up the gravel
  • Pour the water on top of the plate holding it above the fish tank as this makes it even less stressful for your fish.


  • Never use soap to clean the tank as it will kill your fish within seconds.
  • Don't take the fish out of the water unless you're cleaning its home.

Things You'll Need

  • Fish food
  • Fish treats
  • Fish bowl
  • Extra fish bowl
  • Table salt
  • Fishnet
  • Cloth to wipe
  • a box to keep all this in
  • lamp for your fish to see
  • table or stand for it
  • water conditioner
  • decorations
  • extra gravel
  • fish booklet

Article Info

Categories: Goldfish