What is the Best pH Level For Guppies?

A lot of factors can influence your guppies’ well-being, one of them being the water pH. The ideal environment for your guppies should come with stable temperature, pH, and oxygenation, all within the natural parameters that exist in the wild.

The pH, in particular, can make or break your aquarium life. Although guppies are adaptable and resilient fish, capable of withstanding various temperature and pH changes.

That being said, guppies don’t fare too well in environments with living parameters fluctuating too much or too often. When it comes to pH, guppies are the most comfortable, with values between 7 and 8.

These values make the water neutral, providing your guppies with a stable and comfortable habitat. But what happens if the water’s pH drops too much?

Can Low Water pH Kill Guppies?

The lower the pH level, the more acidic the water becomes. Guppies are not fond of waters too low in pH, but they won’t die unless the pH drops too much.

Generally speaking, experiencing lower pH for longer periods of time will cause guppies some health issues along the way. It may also diminish their overall lifespan and cause problems with reproduction.

To prevent these problems, monitoring the pH levels is key, alongside tracking the water temperature, oxygenation, and ammonia levels. Fortunately, water pH doesn’t just drop or increase suddenly or too abruptly.

You should be able to maintain the pH values steady by cleaning the tank regularly and ensuring weekly water changes.

How To Measure the pH Level in a Guppy Tank?

Getting a pH measuring kit should do the job just fine. These are cheap pieces of equipment allowing you to check the pH level on the spot with minimum work.

Most kits will show a gradient with pH values between 5 and 9. This is pretty much the ideal range that most aquarium fish thrive in, including guppies. The only downside would be that the more distant the opposite values, the less accurate the reading.

I suggest getting a pH kit with narrower values that will improve the reading’s accuracy. Or simply invest in a digital pH kit that’s superior to classic pH strips in terms of accuracy.

Can You Increase the pH Level in the Aquarium?

Yes, you can, by using baking soda. One teaspoon of baking soda should be enough for 5 gallons of water. Do the math and stick to the recommended dosage to prevent more drastic pH fluctuations.

There are, however, some points I would like to mention here:

  • Make sure the procedure is necessary – As I have already mentioned, guppies can cope with some pH fluctuations. It’s not an issue in most cases if the values fluctuate only slightly. I would recommend tracking the pH values and only consider raising them artificially if absolutely necessary. The entire process will disrupt your guppies’ comfort, which is why it’s best to avoid the procedure as much as possible.
  • Remove the guppies from the tank – If you’ve decided that the procedure is necessary, you should first remove the guppies from the tank. I also recommend moving them into a temporary aquarium that meets the same living conditions as the main tank. Guppies don’t do well with drastic water parameter fluctuations. Different water temperatures and oxygenation can drop your guppies’ immune system, making them vulnerable to infections, parasites, and illness.
  • Control the pH increase – If you’ve decided that a pH increase is needed, don’t overdo it. Only increase the pH slightly, just enough to fall into the accepted limits. Too drastic pH changes can affect your guppies’ health long-term.

Can You Decrease The pH Level in The Aquarium?

Yes, and you have several options to do that. The most common and straightforward ones include:

  • Peat moss – Place some peat moss in a mesh bag and place it in the water filter. This plant has an acid pH, and it keeps onto its nutrients for a long time. Leaving it in the filter will lower the water’s pH level gradually over long periods of time. You can simply remove the bag once the pH has reached its desired value.
  • DriftwoodDriftwood is amazing for aquariums, thanks to its decorative roles. It’s also useful for decreasing the pH level in the water over time. Just make sure your tank doesn’t have fish species like Rift Valley cichlids who prefer more alkaline waters. In their case, dropping the pH may not be ideal.
  • Boost CO2 – This method works best in heavily planted aquariums, as the plants will work to recreate the CO2 / O2 balance.
  • Decrease aeration – I suggest only resorting to this method in moderation. Your guppies need healthy and stable levels of oxygen more than they need steady pH values.

As a general recommendation, I call for prudency and moderation. While each method is reliable at controlling the pH levels, each can cause issues if mishandled. Follow each procedure’s guidelines to prevent hurting your guppies in the process.


The water’s pH level is key to building a healthy, balanced, and secure living environment for your guppies. Drastic fluctuations in the pH level can stress your guppies, lowering their immune system and leaving them prone to infections and parasites.

The best way to go about it is by monitoring the pH levels in the tank constantly. In fact, you should check all water parameters regularly, including oxygenation, ammonia levels, traces of harmful bacteria, and temperature.

If you see the pH levels dropping or increasing beyond the safe parameters, consider altering the values via one or more of the methods this article has provided. If you still need assistance with the problem, comment below, and I’ll answer asap.

avatar Noah
I’m Noah, chief editor at VIVO Pets and the proud owner of a playful, energetic husky (Max). I’ve been a volunteer at Rex Animal Rescue for over 2 years. I love learning and writing about different animals that can be kept as pets. read more...

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