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Using A Pump To Do Water Changes
Published by Fizz on 20/08/2011 (40457 reads)

Using A Pump To Do Water Changes

If you have MTS (Multiple Tank Syndrome) or have a large tank you may have found that weekly water changes have become a massively time-consuming operation involving manoeuvring buckets and buckets of water from here to there.

One possible solution to help with the large water change is to employ a pump which will move a large volume of water very quickly. This method is useful if you are changing approximately 75 litres or more at a time. There is a ‘one bin’ or ‘two bin method’. Use the one bin method if you are short on space at home.

The links included are for reference purposes – it is always worth shopping around for a cheaper deal (other products/sellers are available!).


Two large food grade bins (or one large food grade bin and one smaller, regular sized bucket).
Large Bin Large Bin with Water
The bin in the picture is food grade plastic and holds 110 litres and can be purchased here:
Other food grade plastic boxes can be found here:

Also Required:
  • Aquarium heater(s) or kettle
  • Aquarium thermometer
  • Tap water conditioner
  • Aquarium Siphon/Gravel cleaner
  • Remote switch device (optional) Purchase here
  • Dirty Water Pump (400w or less) Purchase here
  • A length of hose to attach to the pump if not provided with pump (the hose pictured is a washing machine hose bought from a DIY shop).
Dirty Water Pump


Getting the Water Ready

1) Fill the bin up with the correct amount of fresh replacement water the night before the water change, as this will allow the pH to settle. Add the appropriate amount of tap-water conditioner. If you are using the pump method, it is helpful if you include an extra additional 10 litres of water or so than you intend to use.
2) On water change day, add a heater (or two) to bring the water up to your desired temperature. Make sure the heater does not touch the plastic of bin; either use suction pads or a heater guard. Add a powerhead or pump to ensure that water moves around the heater otherwise the heater’s thermostat will switch it off and the water will not be heated all the way through. Gently replace the lid so that the heat stays in the bin. It can take quite a while for the water to heat up so it would be a good idea to set it up and then get on with something else for a while. The heaters and powerhead (as in the picture below) should be spares that can be used for a QT tank or as spares for your main tank(s).
Bin with Heaters and Pump
3) Alternatively, boil your kettle and add boiled water until the water in your bin has reached the desired temperature. If you are using this method, you will want to do your tank maintenance and cleaning first so that the water is ready to add.
4) Check the temperature using an aquarium thermometer or TDS meter with a thermometer.

Removing the Old Water

1) Carry out your tank clean and maintenance as usual.
2) ‘Two bin method’: Siphon up the old water with as much dirt and waste as possible and siphon directly into your second 110 litre bin. Siphon out the desired amount (equal to the amount you intend to replace). Put to one side for now.
3) ‘One bin method’: If you only have one 110 litre bin, siphon out the dirty water into a smaller bucket and dispose of the water a bucket at a time.
4) DO NOT use the pump to remove the old water directly from the tank. This is not safe for the fish and is absolutely not advised.

Adding the New Water Using The Pump

Once you have removed all the old water you are ready to add in your clean, de-chlorinated and heated water.
1) Switch off and carefully remove the heaters and powerhead (if this method of heating has been used). Be aware that the heaters will still be warm so place them on a heat safe surface.
2) Place the pump in the bin so that it sits on the bottom and is entirely submerged in water.
3) Now here is the tricky bit! Unfortunately most pumps do not come with an on /off switch. Either buy a remote switch like the one suggested in the equipment list or ensure that you are able to safely reach an extension lead to manually unplug the pump. Remember to be very careful when moving water near electrical sockets/extension leads.
4) Before you plug it in (or switch it on) ensure that you are firmly holding your hose so that the water will spray directly into your tank but at an angle. If you point the hose directly down it will cause all manner of disturbance and will also cause water to spray up out of the tank! A 400w pump is very fierce so do not switch it on until you are sure that you have the hose under control. Most pumps will come with a floating switch (it is the round part attached the pump by a wire). Unfortunately, this switch does not work very well in the bins and tends to switch the pump off too soon. The best solution is to hold the switch up out of the water with your free hand (holding the hose with your other hand) until you have pumped back in the required amount of water. If you drop the floating switch it will stop the pump.
5) Be careful not to let the pump run dry. There should always be around 10 litres of water remaining at the bottom of the bin. This was the extra that you added when you set the bin up. Either top up your tank to the water line using a jug (if your tank is not up to the water line) or tip the extra water away.

Disposing of the Dirty Water (‘Two Bins Method’)

If you have used the ‘two bins’ method, you will now have a bin full of dirty water remaining. This is why it is helpful to buy a ‘dirty’ water pump, as it can cope with any waste and fish debris that you have siphoned out. Add the pump to the bin full of dirty water, ensure the hose is pointing down a drain (preferably outside because it comes out with some force) or out onto a garden and switch on. The dirty tank water will pump away, leaving you with a small amount in the bottom of the bin to tip out manually.
Although this method may sound complicated at first, it will allow you to pump a large volume of water into your tank very quickly which means less time and effort heaving buckets to and fro.


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  • Tropical Moderator

 Re: Using A Pump To Do Water Changes

Very helpful guide Fizz

  • Home away from home

 Re: Using A Pump To Do Water Changes

Thanks Noodle It's really nice to be able to contribute something to the site! I've found so many of the articles so incredibly useful over the years

  • Tropical  Adviser

 Re: Using A Pump To Do Water Changes

Great article Fizz. I'm sure this will come in very handy to link to in the forums

Thank you!

  • Home away from home

 Re: Using A Pump To Do Water Changes

That's great, very informative.

  • Home away from home

 Re: Using A Pump To Do Water Changes

Great article and very useful - Thanks!

Another tip for getting rid of the dirty water is to add a length of hose (kept purely for this purpose) to the end of your water syphon/gravel cleaner and aim the other end straight down the outside drain or onto your garden (note this only works if the far end of the hose is at a lower level than the tank water) that way you don't need the second bucket - but be careful if you have small fish that you don't accidently suck any up (put some fish netting over the end of the hose if you need to).
Shaz x

  • Just popping in

 Re: Using A Pump To Do Water Changes

Very useful.. Thanks

  • Home away from home

 Re: Using A Pump To Do Water Changes

Brigitte reminded me that when you receive your new bins it's really important to give them a rinse out first because they do smell very 'plasticky'. I also found a couple of tiny bits of plastic in one of mine and this is the kind of thing that you don't want getting into your tank and being mistaken for food!

Make sure that if you clean them through you don't use detergents; a mix of lemon juice or vinegar and water should be fine.

Also, it is also a good idea to flush through the pump a few times to check it is working but also to make sure it is 'fish safe'. Brigette has informed me that the hose that comes with the one linked in the article is perhaps a bit too 'plasticky' so perhaps purchasing a washing machine hose or a garden hose to attach to your pump is a better option.

I would advise using your judgement. If you don't think something is safe to use with fish (or will affect the water) then err on the side of caution.

Thanks to Brigette for the updates!

  • Home away from home

 Re: Using A Pump To Do Water Changes

Here is a picture of the pump I use for the water changes and the washing machine hose that I added to it.

Resized Image

  • Home away from home

 Re: Using A Pump To Do Water Changes

I use this: ... 0T9R2GC/ref=cm_cr_pr_pb_t

It's not overly powerful, so doesn't bother the fish (oddly enough my cherry barbs actually seem to enjoy it!!), but it's capable of transferring the 50 litres I use for a water change in just over a minute. It's got a filter in it so OK to use for dirty water - I usually stand it on a brick in the bottom of the container so it doesn't suck up too much sediment and clog the filter. It doesn't have a float switch, but I use a remote control socket adaptor to turn it on and off.

  • Quite a regular

 Re: Using A Pump To Do Water Changes

Re the bins, I was in B&Q the other day looking for bins for exactly this perpose found an 80l one for ?11 and thought this will be ok to be going on with. As i was heading to the check out with said bin walked past some plastic boxes that hold 70l, but have wheels on them. Perfect I can fill them up in the kitchen and then wheel them through to/from the living room to fill and empty the tank. Also the have the added benifit of being shallowrer and wider than a bin so its easy to get right to the bottom to tip the last little bits of water out. Havent purchased a pump yet as my tank has set its own agandea when it comes to cycling ( see my other posts )but am getting perpared for the big day. Thought these boxes were perfect for the job. (Ive got a 190l tank so 70l was just right)

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