Best TDS for Guppies – Complete Guide

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TDS is an important water parameter for all sorts of fish species. If you own a number of guppies in your personal aquarium, you might want to know what is the best TDS for your fish. In today’s article, we’ll talk about the best TDS for guppies, so you’ll know how to set these levels.

TDS is short for Total Dissolved Solids. In other words, TDS is a number that lets you know the quantity of organic and inorganic particles present in your tank’s water. TDS is measured in part per million (ppm).

First of all, let’s see what is the range for TDS where guppies feel most comfortable in:

From my experience, the best TDS for guppies is between 400 and 600 ppm.

It’s true, guppies can support a TDS range of 200 to 1000 ppm. However, to make sure your aquarium is best suited for guppies, you must keep the range between 400 and 600 ppm.

I’ve also wrote a guide on how water pH level affects guppies, and how to adjust pH level in your aquarium. Check it out the linked article.

Now that you know what the ideal levels of TDS are for guppies, let’s see how does TDS affect guppies:

Does TDS Affect Guppies?

TDS will affect most fish species, meaning that guppies are no exception from this rule. How though? Guppies are a popular fish breed, that will live happily in a well-cared for fish tank.

This means that TDS levels should also be taken into consideration when dealing with guppies. How does TDS affect your guppies?

Usually, higher a TDS level means lower levels of oxygen in the tank. How is this possible?

This happens because when TDS gets higher, oxygen will be harder to be maintained in the water. Basically, there will be less space left for clean oxygen molecules in the water.

Since this is the case, your guppies will be affected directly. How? Less oxygen in the water will affect your guppies in a negative way, because breathing in the aquarium will get harder.

Also, since breathing gets more complicated, other health problems could appear as well.

Basically, maintaining a proper TDS level in your tank is crucial, if you want your guppies to live a healthy life. To do this, first of all you must know how to measure TDS in your aquarium. Let’s see how this is done:

How to Measure TDS?

There is a simple way that people generally use to measure TDS levels in their water.

The first thing you need to do, is get a TDS meter. This is a digital device that will measure TDS levels in your tank instantly. How does it work?

There are many companies who produce these devices, but the general work process that you need to follow is this:

  1. Measure the temperature of the water, by immersing the device in the water to the maximum immersion level (usually 2 inches)
  2. After measuring the temperature, set the device for measuring TDS level. This is done with the press of a button in most cases.
  3. Immerse the device in the tank again like you did before. This time, it will show the exact TDS level written on the screen.

As you can see, this method is easy and straight forward. To make sure you choose a device properly, I recommend this device from Amazon. It is a simple yet powerful product, used by many aquarium owners efficiently. It works just as I described above.

Now that you successfully measured TDS in your tank, you should know how to reduce the resulted TDS level, if it’s too high (this happens most of the time).

How to Reduce TDS in Your Aquarium Water?

To reduce TDS levels in your aquarium water, you can do at least 3 things. Let’s see each of these separately:

1. Don’t overfeed your fish

This method is pretty simple and easy to understand, because overfeeding will result in large quantities of organic and inorganic particles to be left in the tank. It’s best to only feed your guppies as much as they can eat in about 3 to 5 minutes.

This way, you make sure the food won’t be left behind, and TDS will remain at proper levels.

2. Do regular water changes

Regular water changes are essential to keep TDS levels in check. If you don’t change your aquarium water regularly, great amounts of waste can pile up in the tank.

Of course, this will result in higher TDS levels. Be sure to change the water regularly, to keep everything in check.

3. Do regular aquarium maintenance

Besides changing the water, you also need to clean the tank itself from time to time. This is needed, to get rid of every bit of waste that might stick to the tank’s substrate or walls.

This is actually the most important step, because a dirty tank will surely contain higher levels of TDS.

Why is TDS Increasing in Your Guppy Tank?

Now that you know how to take care of high TDS levels, you might be wondering why does TDS increase in your guppy tank in the first place? There are multiple reasons for this.

The most common explanation for TDS increase is the use of tap water. Such water will come with a higher TDS level from the start, and if you don’t do the steps I mentioned above, TDS will increase much more quickly in the aquarium.

Another common reason is the use of fertilizers that will make their way in the water you’re using. Fertilizers, even in small amounts will greatly impact TDS in your tank, because they contain a lot of mineral left-overs. To get rid of these, make sure to change the water as mentioned above.

Fish waste is another cause for high levels of TDS. This will appear in any tank, and even more in aquariums where the owner overfeeds its guppies. The water filter can also build up waste, so make sure to clean the filter regularly, to get rid of unwanted waste.


All in all, TDS is an important factor, you need to keep in check when owning an aquarium. As seen above, many things can cause a spike in TDS levels.

I recommend that you apply all three methods described above to reduce TDS in your fish tank. This way, your guppies will live a long and healthy life.

Updated: April 7, 2022
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