How to Lower PH in Aquarium – 8 Actionable Methods You Can Do Today

Last Updated on July 27, 2021 by cmoarz

Ph in your aquarium can be a pain to deal with. Ph level fluctuates endlessly for hundreds of reasons. Sometimes you just need to lower the ph to bring it back in line with the balance you are looking for. So I’ve put together 15 actionable methods you can do today that will lower the ph levels in your tank!

Method 1: Drift Wood

Adding driftwood to your tank is a fantastic way to lower the ph in your aquarium. It’s also one of the most widely recommended methods for a freshwater aquarium. By adding driftwood to your tank, you are adding tannins.

Tannins in the water will chelate (or bind) with things like calcium and magnesium that can disrupt the ph balance of your aquarium.

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The best part about using driftwood is that it also adds beauty to your aquarium as well! Driftwood can be used to create a natural, biotic environment that your fish will love.

The best types of safe aquarium driftwood are:

  1. Pear
  2. Oak
  3. Hawthorn
  4. Heather
  5. Alder
  6. Cherry
  7. Birch
  8. Beech
  9. Sycamore
  10. Apple

All of these will work very well for lowering the ph in your aquarium. However, there is some type of driftwood that you should avoid adding to your fish tank to try and lower ph. It’s not worth it and can do more harm than good. These are:

  1. Horse chestnut – May be toxic
  2. Spruce – Leaks sap, avoid
  3. Yew – harmful to fish
  4. Cypress – Pros say to avoid, also leaks sap
  5. Ivy – harmful to fish
  6. Walnut – Pros say to avoid
  7. Pine – Leaks sap and is messy, Avoid
  8. Grapevine – Decays very quickly
  9. Cedar – Pros say to avoid
  10. Lilac – harmful to fish

It should also be noted that adding any driftwood to your tank will release tannins into the water which will turn your water a shade of yellowish-brown. Some people like this, Fish certainly do. But some do not.

However, the amount of tannins released depends on things like the temperature and size of the driftwood itself. So it’s best to slowly introduce driftwood into your tank over time.

Be sure to do several long boil sessions of your driftwood before placing it in the tank to try and boil off as much tannin as possible.

If the tannins get out of control, you can read our article here on how to remove them.

Method 2: Almond leaves

Indian almond leaves are one of the most popular choices for bringing down aquarium ph levels. Not only do they do a good job, but they release significantly fewer tannins than driftwood or peat moss will.

Almond leaves are also highly effective at absorbing ammonia and nitrate as well. It’s a win-win in my book!

Adding almond leaves to your aquarium is just as easy as adding any other type of loose substrate. Fill the pot with a layer of black gravel, then place the leaves on top of that like you would peat moss or something similar.

Almond leaves will have your water reading at a lower ph in around 3 days, which is pretty impressive!

Now it should be noted that you CAN overdose your tank on almond leaves! You should keep to the general rule of thumb of 1 almond leaf per 10-gallon tank and even less for smaller tanks. This will keep your ph from crashing too rapidly even for your soft water fish, as well as keep the tannin levels down.

If you wish to raise the ph in the future, Remove the almond leaves.

Method 3: Cappata Leaves

Now the things I’ve heard about cappata leaves are that they lower ph, but don’t tannin your water as much. Cappata leaves are also known to harbor anti-bacterial and anti-fungal properties which may keep your tank even healthier.

They are very popular in the Asia fish-keeping world because of these unique properties. They can help fight off bacterial infections and all sorts of positive effects.

Cappata leaves release quite a few tannins, and it’s recommended you boil them first before using them in your high ph tank. Even after boiling though, You should expect to see a color change very quickly.

Aside from lowering the ph level in your high ph tank, they also serve as a good food source for smaller fish and fry as they develop a nutrient-rich biofilm that the fish can eat.

Method 4: Oak Leaves

Oak leaves are the last leaf on this list. They aren’t nearly as powerful as the other leaves like the cappata leaves, but they will do a better job than driftwood at lowering your high ph.

Oak leaves also work very quickly to help bring your tank down to normal levels. They have significantly fewer tannins than either almond or cappata leaves and are more effective in this sense for improving water quality while keeping it healthy.

Do note that because they are weaker, You may need to add a lot more leaf litter to the aquarium to get measurable ph changes in your tank water. Overall, they are a great natural way to lower the ph in your aquarium, and, honestly, they look really spiffy.

Method 5: Reverse Osmosis

This is an extremely expensive filtration method that can help keep ph levels down for much larger aquariums.

Reverse osmosis basically involves running all aquarium water through a filtration system that removes *everything* from the water. This means not only does it remove impurities, but bad elements in your water as well.

Maybe if you have an expensive home-sized aquarium and don’t mind spending a few hundred dollars to get things flowing again after the cycling process (as this will raise your ph before your cycle is done anyway), then you should consider reverse osmosis. But for most hobbyists, this isn’t really worth the money or hassle just to normalize high ph levels in the long term.

Still, if you are interested, we recommend this filter system.

Method 6: Peat Moss

Peat moss is almost as good as driftwood, but it also produces a ton of tannins.

For this reason, you might want to couple smaller amounts with driftwood or another thing on this list than fully relying on peat moss alone.

Also, peat moss isn’t as good for bacteria and keeping things healthy as the other methods are, but it is a great initial experiment before committing to something more expensive if you don’t want to spend extra money.

Try adding 2 tablespoons of peat moss per 10-gallon tank and see how your levels look after an hour or so. If the ph still hasn’t dropped significantly enough for your taste, add in another 2 tablespoons or repeat this step again in a 12 hour period. That should lower the ph gradually over time pretty nicely without causing too much tannin release.

Method 7: Use a different water source

Tap water is desalinated sea water so we use bottled water for our tea and coffee
“water” by Risager is licensed under CC BY-SA 2.0

The regular water you use in your aquarium could have high ph levels already. If this is the case, no amount of water changes are going to help when it comes to high ph tap water.

Consider moving to a different source of water, or away from tap water altogether and opt for buying distilled water. Certainly, this would be one of the more expensive options on the list as every time you want to do a water change you will need to run out and buy water!

You could always make your own distilled water as well. However, this is a hugely time-consuming process and there are better ways to deal with a high ph of water.

Method 8: Using commercially available chemicals

This is by far one of the best methods aside from driftwood and works in a pinch if you can’t find other items on this list.

These chemicals help bring your ph levels down by quickly dissolving the carbonate and bicarbonate ions in your water. It’s important to note that these aren’t organic supplements, so they don’t affect pH levels as such, but they do lower your ph quickly and effectively without any extra work from you.

The best part is- these are approved for aquariums! So you can buy them if you have a local pet store or hardware store. Just make sure it is safe for your fish first before buying something with other fillers in them.

Otherwise, Amazon has some really common choices for lowering PH levels which are also inexpensive (and free shipping).

Important notes for all of the methods above

No matter which method you choose to use, It’s important you know what ph levels and acidic levels your fish can tolerate and prefer.

Keeping a natural, stable ph level is the main goal here, as this is where the majority of your fish will thrive.

In fact, any time you hear about fish dying from “high ph” it’s most likely because someone was trying to keep their levels artificially low with drastic methods like using chemicals or running aquarium water through a reverse osmosis filtration system (which we don’t really recommend for beginners).

If it said high acidic levels in a pet shop or hobbyist forum, then it is almost always referring to something other than hard water. These are usually parameters like Nitrate/Nitrite and Ammonia which should be monitored separately anyways!

It’s also important to test the water level in your aquarium often with a test kit. It can be as simple as a test strip kit or a full-blown state-of-the-art water test kit. They both work fairly well.

Maintaining a balanced ph will require a lot of testing, and often. You need to keep track of ph, alkalinity, etc and adjust accordingly.

Everything you do to lower ph levels requires some type of adjustment.

For example, if you are using a chemical to lower your ph, it will make the KH more basic and you may need to add another chemical to bring this level back down. And so on..

Therefore, understanding how these things work and what adjustments you need to make is imperative. 

One of the reasons aquariums have such a bad reputation for being difficult is that people don’t take into account how everything interacts with each other in a closed system. Everything you add into your tank has an effect on your water perimeters.

Even things as simple as carbon filters, oxygen stones, and more complex setups for carbon dioxide can have drastic effects, so keep in mind.

This also means that keeping good records of all of your tests can really help give you an idea as to how your tank works overtime! Don’t be afraid to experiment either. Once you understand how things work together, then you can start to make educated decisions as a beginner aquarist.

So what methods do/did you use for lowering ph levels? Let us know in the comments! Thank you for reading, and we hope this helps all beginners out there on their fish-keeping journey.


Owner of and also owner of actual Aquarium Gravel believe it or not! ;). Setting up beautiful aquarium sceneries and habitats since I was very young. Enjoy!