Water changes are an integral part when keeping fish in an aquarium. Failure to carry out adequate water changes will result in poor water quality which can make your fish more susceptible to disease and even death.

If your aquarium is big enough, stocked properly and you feed your fish sensibly then nitrate levels shouldn't reach high levels within a weekly period. In reality you shouldn't really need to change any more than one third of the water each week. However we all know that overstocking aquariums is quite common and therefore nitrate levels will be that much higher at the end of the week. In these cases water changes will need to be slightly larger. It's quite easy to work out, if you test your water for nitrate and the readings are 40 ppm, it will take a 50% water change to reduce the nitrates back to 20 ppm.

If you have tested your water and your nitrate levels are extremely high level instead of carrying out a huge water change, you might be better off carrying out several smaller water changes over a few days. Sometimes fish that have been housed in an aquarium with high nitrate actually get used to being exposed to these high levels. If you were to suddenly change a massive amount of water all at once, it has been known for fish to become shocked and die. I don't think this is a common occurrence but it's something you should be aware of.

It is important that you carry out a nitrate test properly and read the instructions fully. This video will show you exactly how to carry out a nitrate test

Using buckets to change water in a large aquarium is very time-consuming. However, there are products you can get that will make the water change a piece of cake. One such product is called the and is extremely popular amongst many of our members.