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How to reduce water changes for your fish tank

Water changes are no fun in the aquarium hobby, especially if you are dealing with large tanks. If you are looking for ways to reduce having to clean your aquarium, you can check out this guide for some help.

Test your waters

If you have been blindly doing a set amount of water changes, then there is a chance that you are doing too much of it. A vast majority of fish species in the aquarium hobby will do fine in an environment that has 0 ppm of ammonia, 0 ppm of nitrites and less than 40 ppm of nitrates.

The only way to know these measurements is to use an aquarium water test kit (if you don’t have one you can purchase the API Master Test Kit with this link on Amazon). If the parameters show that the fish tank is safe for your aquatic pets, then you can move out less volume or even skip doing a water change altogether.

Low Bioload

Another way to slow down the frequencies of water changes is by having lower bioload, which is the amount of organic wastes being produced by the inhabitants of your fish tank. In general, bigger fish produce more wastes when compared to smaller fish. With that said there are a few nano fish (such as Mollies, Platies and Plecos) that add a lot to the bioload despite their small frames.

The wastes will eventually end up as ammonia, nitrites and nitrates. Even if you have a fully cycled tank to get rid of the ammonia and nitrites, you most likely need to swap out water in order to reduce nitrates. So make sure you don’t overstock your tank if you don’t want to do too many changes.

Uneaten food also contribute to your bioload. Most fish keepers tend to overfeed their pets. To prevent dirtying the water too much, you should feed based on how much your fish can eat within a few minutes and remove any uneaten portion from the tank.

Tank Sizes

Bioload is also tied directly to the size of your tank. The more water volume you have, the more your aquarium can dilute any spikes of ammonia, nitrites and nitrates. As a result, you can go longer between having to service your aquarium. You can check out our tank size guide for more information.

Keep in mind that there is a little bit of a tradeoff. While you don’t have to do water changes as frequently, you do have to swap out more volume in bigger tanks in order to get the same percentage of change as a smaller tank (i.e. you need to change 11 gallons of water from a 55 gallon tank as opposed to 2 gallons of water from a 10 gallon tank for a 20% water change).

Live Plants

You should also consider getting live plants for your aquarium as they will help consume ammonia and nitrates. The same plants will also provide surface area for your beneficial bacteria (which will help reduce ammonia and nitrites) to grow as well.

If you are new to keeping plants in your tank, a few beginner-friendly species we recommend getting are Java Fern and Java Moss. Both of these do not require a lot of lighting and do not need to be planted in the substrate. We also highly recommend that you get Pothos and dip its roots into your tank water (you can find out more about this houseplant in our dedicated guide).


While this may be a little controversial, we also prefer adding snails to our tank. These creatures will eat any uneaten food in your aquarium.

The problem most people have with snails is that some species will reproduce rapidly, which may result in them taking over your tank if you aren’t careful. To prevent a population explosion of Bladder Snails, Ramshorn Snails and Malaysian Trumpet Snails, you should make sure that you aren’t overfeeding your fish dramatically. Alternatively, you can get Nerite Snails if you have a freshwater tank as their eggs won’t hatch unless they are in brackish water.

Surface Agitation

You should also consider increasing the surface agitation of your tank waters. The beneficial bacteria need oxygen to thrive while your live plants need carbon dioxide to grow. Both of these come into your tank water through the air. By stirring the surface of your water, you will increase the gas exchanges.

To have more surface agitation, you might want to get an air stone. You may also want to position your filter output to above the water line.

Seachem Prime

Although many fish keepers view Seachem Prime as mainly a water conditioner that remove chlorine and chloramine from their tap water, this product also has an extra feature to help you reduce the amount of water changes. The solution can bind the ammonia, nitrites and nitrates to make the nitrogen compounds safe for fish at up to 48 hours.

If you don’t want to do a water change, you can dose Seachem Prime every 24 hours. With that said, the chemical is not designed to remove ammonia, nitrites and nitrates as the compounds will remain in your tank after Prime wears off. So you will eventually have to do a water change.

If you don’t have the product already, you can purchase Seachem Prime on Amazon.

Crushed Corals

Your fish tank will get more acidic over time due to the organic wastes being produced. This will lower the pH of your water parameters, which may harm your fish if it is out of your pet’s comfort range.

To prevent your water from getting more acidic due to the lack of water changes, we recommend using crushed corals. These will leech elements into the tank water that will increase and eventually stabilize the pH of your tank water.

Aquarium Top

If you don’t have one already, then we recommend getting a cover for your fish tank. This is because water can evaporated more rapidly if you have an open top, which means that you end up with higher concentrations of ammonia, nitrites and nitrates left behind. To find out other benefits of covering the top of your tank, you can check out this guide.


To do less water changes, you should keep the bioload low by having less waste producing fish. You can also make sure not to overfeed your pet and have uneaten food laying around. Furthermore, you should add live plants to help clean your water. Seachem Prime is also helpful as a short term solution as the chemical will detoxify ammonia, nitrites and nitrates at up to 48 hours per dosage.