4 Simple Ways To Lower Aquarium pH Naturally 24

Share This On

Aquariums can be a fun and beautiful addition to any home or business, but keeping your aquarium in good shape and your fish happy and healthy can rely on many factors. The most important of those factors is, in fact, the pH level of your aquarium.

To simplify it, there are two ways your aquarium’s pH balance can be thrown off, and many reasons why they can occur. Your aquarium’s pH can be “normal”, “low”, or “high”, and they each mean something different.


  • What is “Low” pH? – A low pH means that there is an increase of hydrogen ions, making the water more acidic.
  • What is “High” pH? – High pH is due to too many hydroxide ions in the water, making it more alkaline.
  • What is “Normal” pH? – that’s a funny question. As About.com put it, there is truly no “normal” pH amount. There is an optimal pH amount of (approximately) between 5.5 and 7.5 for freshwater fish, but due to the variance of fish species and preferences, you may have some research before picking fish.

Why Does pH Increase or Decrease in My Aquarium?

There are many reasons why your aquarium’s pH can be off balance, even unexpected things, like the type of gravel or substrate, which can change the pH balance. Decorations are notorious for changing the pH of a tank, and even putting a new water filter in or filling up the water in the tank from a different source can cause problems, so it is important to consider these features before making any changes to a good pH balance.

Substrate and Decoration Problems

Changing the gravel in your aquarium can be one of many causes of a change in tank pH. Because there are so many different types of gravel, make sure that you have the proper type for your fish. For example, crushed coral can be very appealing to the eye, but is best for being used in marine aquariums where fish enjoy a higher pH, but can harm lower pH fish.

Likewise, shell, rock, and other decorations can sometimes leak minerals or dyes into your aquarium, causing a toxic reaction that can be fatal to fish. Make sure you’re getting colorfast inks and dyes in your aquarium decorations.

Water Source and Filter Problems

Even doing a good deed like changing the water in your aquarium can change the pH. If you use a different water source or change a filter, the pH of the tank can vary greatly. The key is to use as little chemicals in the water added to your tank and filters as possible, even tank-specific chemicals meant to help balance out pH as they can drastically change pH.

Four Ways to Raise or Lower pH Naturally

Luckily, there are as many ways to change the pH for the better as there are to accidentally make it worse. The best way to change it is the natural method, as opposed to the chemical method. The chemical altering of pH from the introduction of store bought chemicals can actually alter pH either too much or too drastically – both of which can result in fish illness or death.

The natural way is quite simpler, doesn’t involve harsh chemicals, and won’t make immediate drastic changes that could harm your aquatic life.


Adding a piece of natural driftwood to a tank community can gently help lower pH levels. It is, however, a great way to color your tank’s water, so to avoid that, it is recommended that you either soak your driftwood in a separate container (completely submerged, not floating) for 1-2 weeks prior to introducing it to your tank, or boil it to sterilize it.

Adding Driftwood - Simplest Way To Lower pH Naturally

Adding Driftwood – Simplest Way To Lower pH Naturally

The wood acts as a filter for the water similarly to how the leaves of a tree would filter air, in that the composition of the tree acts as a natural filter for contaminants, or, in this case, the contaminants in water that raise the pH value of your tank.

Driftwood sold for reptiles may look great but can also contain chemicals harmful to fish, so make sure that you are purchasing the correct thing.

Peat Moss

Peat can also be a great way to help naturally filter the pH levels of your tank, but, again, can discolor your water. Many aquarists recommend pre-treating your peat moss in a separate bucket for a few days before putting it into your tank in order to dissipate the yellowish tinge that natural peat can give water.


Try adding peat to naturally lower pH

Peat moss can be added to the filter in pellets or chunks that you can purchase at any pet or gardening store, and can naturally lower pH by acting as a second filter. Putting them into a filter bag (or use women’s panty hose as a filter bag) or inside your water filter itself is highly recommended.

Adding Peat Moss to your filter

Adding Peat Moss to your filter

An addition of peat to your tank, whether in natural moss form or pellets, will gradually lower pH over time, so if you’re doing weekly water changes, you might not notice as much of a difference as people who change their water less frequently.

Depending on how hard your water is, you will have to experiment to find the right amount of peat for the size of your tank in order to reach your optimal pH level.

Almond Leaves (Catappa)

Catappa is a type of Indian Almond leaf that acts as the “poor man’s water conditioner,” softening and lowering the pH. Almond leaves can also release an amount of tannins in the water, so you may want to soak them to get the color leakage out prior to adding them to your tank. However, the color difference can usually be fairly subtle, especially compared to other methods that release colored tannins into the water.


Almond leaves – an easy and natural way to lower aquarium pH

Also, Catappa will, without fail, help to naturally lower the pH balance of your tank by filtering the water just as they filter contaminants out of the air. There is also some speculation that almond leaves work as a natural health aid in aquarium fish, and some say that it can prevent or cure disease, working as an antioxidant and anti-inflammatory, but the clinical research to support such claims is still in progress and not yet fully confirmed.

Almond leaves can also be a great aesthetic addition to a tank, especially for fish that are used to a native habitat in a river, lake, or other body of water with lots of natural clutter. Fish love the natural hiding spot and ecological impact that leaves can have on their environment.

RO water

RO water refers to Reverse Osmosis, a process of water purification involving (according to Wikipedia.org) the use of a semipermeable membrane that removes many types of molecules and ions, resulting in fresher, softer water.

The filter allows water and smaller ions to go through while keeping the heavier, larger ions like lead, chlorine, and other water pollutants filtered out for the most part. A good RO system can cost a few hundred dollars, but it is a natural deionizing process that can be used in aquariums easily.


Recommended RO unit: Coralife Pure-Flo

An RO unit will help provide a constant, stable pH level, and can filter up to 99% of water contaminants. An RO system will need occasional filter replacements, but is a great long-term solution if you have hard tap water and your fish are not happy in it.

So whether you choose an aesthetically pleasing method like driftwood or almond leaves, or an additional filtering process like peat moss or an RO system, never fear. You can gently and naturally control your tank’s pH with a little information and a little time.

Let us know how these methods work on your tank by commenting below, and be sure to help your aquarist friends choose the natural way to balance out their tanks’ pH.

About Dennis Hanson

Dennis is an experienced aquarist with many years of knowledge and experience in keeping successful tanks. He also has no relations to the pop group Hanson.

24 thoughts on “4 Simple Ways To Lower Aquarium pH Naturally

  1. Reply Scott Shultz Oct 11,2013 2:03 am

    Hi….I have been trying for years to keep Clown Loaches in my tank….probably have purchased over 40 of them and every one of them ended up dying anywhere from one month to 2 years after the purchase. While I have always had fish tanks, all of the ‘experts’ said to keep the PH at around 7.6 for community fish. I have just found out that clown loaches thrive in a tank with a lower ph of 6.5 to 7.2, roughly. Since my water is hard where I live in Madison, WI, and want to get more of these and other kinds of loaches for my 75 gallon tank, if I get a RO system under my sink, I am guessing I should change the water once a week at a 10% change….until the PH is much lower. I have always used the chemical PH Lower to lower the ph but will never purchase this product again….it just does not work. I also have a 37 gallon back up tank….so when I am ready to buy fish again, should I put the new fish in this back up tank for a week or so? Thanks-

    • Reply Dennis H. Oct 28,2013 9:30 pm

      Hi Scott,

      Clown fish are very sensitive to poor water condition, higher pH level might not be the only problem here. If water quality degrades clown fish will be the first one to get effected by it. Moreover they need to be in school of 4 or more.

      Coming back to maintaining pH, I will not suggest using pure RO water for aquarium since it lacks elements and there is no hardness in it. What you can do is, mix hard water with RO water. Now this is also tricky and needs some experiments before you come up with the ratio which gives you the water having pH level as per your requirement.

      Still if you wanna go with pure RO then a buffer needs to be added to the water to ensure the water parameters are suitable for your fish. These buffer are easily available at your LFS.

      Also you can change water more frequently, maybe twice a week or you can change water somewhere between 15 to 20% once a week.

      Hope this helps. Cheers!

  2. Reply Tom A Dec 15,2013 4:06 pm

    Hi, I am starting up 20 gal. high tank and am interested in adding driftwood. I live near the ocean and have many pieces I collected over the years. If I soak them or boil them can I use these safely in my tank? Thanks

    • Reply anne j Jan 25,2014 12:54 am

      for the driftwood, pick pieces that are as white as possible in color= less tannins left in wood.Under a running water scrub with a bran new brush till all dirt is gone.Dont use the brush for anything else. Place the pieces in a large pot, or a deep steam table pan, -you can get these from a restauraunt supply business —cover with filtered water over the pieces or till they float, and put a top on it and sit on stove burner’s and boil for 1 hour. Check and change water and boil for another hour. If the water is still dirty then try another piece or you will have to keep boiling till the water comes out a very weak color of tea. Rinse in cool using filtered water and then- when cooled-add to tank.

  3. Reply Rich Jan 6,2014 8:42 pm

    Hi, all the recommendations here are to lower Ph. Luckily for me, that’s exactly what I need. Thanks for these suggestions, they look great and I’m anxious to try them out. However, some people may be interested in raising Ph.

    • Reply Dennis H. Jan 6,2014 8:43 pm

      Hi Rich, glad you found this article useful and thanks for the suggestion!

      • Reply Rich Jan 6,2014 9:32 pm

        Thanks Dennis! Just ordered driftwood. I have an aquaponic system, so I’m going to start using peat moss in my plant baskets.

  4. Reply Sara Jan 14,2014 3:26 pm

    Is there a natural way to increase your PH? My tank (10g platys & mystery snails) is currently very acidic. I bought some Proper PH, but was directed against using it. So is there a way to raise it that doesn’t involve metal-based means?

    • Reply aj Feb 6,2014 3:17 pm

      sara, used crushed coral in a part of your filter or just add water washed/scrubbed sea shells. Over time it should go down. Use API test kit to moniter your perameters. Ph up/down are for temporary use and it is best to just raise ph or lower ph naturally.

    • Reply Dennis H. Feb 15,2014 2:05 pm

      Hi Sara,

      I suggest you use a calcareous rock to increase your PH. The calcareous rocks release minerals in the water which will raise your PH.

      Also you should check your KH, if it’s too low your PH will be really unstable.

  5. Reply NEIL WATSON uk Jan 31,2014 8:10 pm


  6. Reply Brian Feb 12,2014 4:03 pm

    Is all peat safe? I bought product called black gold Canadian Sphagnum Peat Moss Plus label says its organic and has OMRI listed on it also.
    it says it has a organic wetting agent added to it 0.0001% Yucca extract
    I have very hard water.

  7. Reply Brian in Ohio Apr 17,2014 7:20 pm

    You mentioned RO water filters to lower PH. What will a De-ionizing filter do to lower PH? Would it be wise to use it to lower PH levels?


  8. Reply Rob B May 16,2014 1:05 am

    I do have a RO system for drinking and I can confirm that it does in fact drop the PH level significantly. From 7.6 to 6.4. I inherited a 20G community tank, that I’m still trying to find out what kind of fish are in it. A Few Guppies, neon’s, nothing too exotic. That being said, I found myself guilty of over feeding after a while and one of the larger fellows began to swim tail down. From what I gather, it may be a bladder infection and I’ve had no luck trying to feed it a pea. The PH level was above 7.6, so I assumed the ammonia was too and did a40% water flush and thinned out the feeding. Finally did proper nitrate test and found it to be 0 after the flush, but the PH is still high between 7.4 – 7.6. Just finished reading this article and happened to have some peat moss that I added into the filter, so I will see what happens in few days. Curious about the gravel, which is store bought. Wondering if you could shed some light on this. Also I wonder about the plants, which are again store bought, but likely some degree of plastic. Might just take them out and see where things go if the peat moss is not able to lower it. Given that the RO drops the ph down around 6.4, yet the tank is at 7.6 there is obviously something raising the level.

  9. Reply Jose Jun 17,2014 8:56 pm

    jose Jun 17,2014 8:51 pm

    I have 75g tank with many corals and fish I find that my PH is 7.67 in my monitor some people said the right PH level is between 8.1-8.4 I check my alk and that is high I cant put no more baking soda but my PH is low wat I can do to make my PH righ leve,because is nothing wrong in my tang befor I never read the PH now Im worry about that.Thank you for your time, Jiose

  10. Reply Candz Jul 29,2014 6:05 am

    Hi ya! So im new to all of this I have a freshwater tank an I wanted to ask how to work out the ph
    …I have a kit to test ph low and ph hi, but how do I test just ph so I can keep it at 7.0???

  11. Reply Matthew Jul 31,2014 4:24 pm

    Hello I have about 20 tanks that I breeding numerous apistogrammas and discus and it is very important to keep the ph at 6-6., if you have the time try collecting rain water to do a larger water change, then when you go to do water changes use RO with a buffer in it….it works great… but all the other methods work as well its just time consuming and may take alittle longer to work. thanks ahraquatics/facebook

  12. Reply BJ Aug 30,2014 6:38 pm

    Hi I have a 75 gal Fish Tank and there are around 40 Butterfly Koi and Regular Koi in it I am having trouble with high PH. I have tried backing soda and it lowers it for a while but then it goes back up I add water to it and I Put live plants in and every time I do something different it will raise the PH. IS THE RO DROPS THE BEST WAY TO LOWER THE ph. And is the peat moss that grows on rocks and trees safe to use and is it the same thing you get in fish stores ? Is a high PH ON A TEST STRIP safe for my Koi? This fish tank stuff is new to me
    Thanks BJ

  13. Reply Gtoguy Nov 8,2014 3:05 am

    Bad news BJ, it is not safe. A high ph is toxic to your fish. Watch out for overstocking your tank. Koi, especially the butterfly koi need space and their water soon gets polluted if not carefuly monitored. Safely do a water change and increase your biological filtration efficiency. Remember to change out your active carbon as this will chemically filter the water. Do not use moss from outside. That is not peat moss. Coco peat can be found in most hardware stores. Koi will destroy your plants sooner or later. Unless they are vegitarian…and I’ve never seen one of those.

  14. Reply Fred.P Nov 17,2014 11:02 pm

    HI I have a 60 gallon tank the ph level occasionally from day to day will drop down and the water ph taste reveal color yellow. Now I have been putting ph up in the aquarium to normalize the ph then a couple days later its back to being yellow again. Could this be to too many fish in the tank I have like plus 15-30 fish or be something else. I usually do weekly filter changes and do monthly water changes. Any advise or help anyone can give I take at this time.

  15. Reply William Bennett Jan 27,2015 6:15 am

    A simple solution, as well as cheap, is to add 1 tsp, pure baking soda per 55 gallons/freshwater. This will drop pH by 0.2/< which is the max recommended pH +/-. I have had the most trouble over the years with this same issue. What the manufacturers of these "ideal aquarium chemicals" fail to inform you is that these pH parameters do exist and scaleless/cutaneous gas exchanging freshwater organisms are especially susceptible to the harmful side effects of these chemicals. Go with the most natural method possible!!!!!!!!! One of the best/safest methods I have discovered is the addition of distiller water (minor pH drops) or "Check" brand "soda water (larger pH drops {<0.4 ppm with addition of 1 cup soda water in 55 gal/H2O @ 8.0ppm". Don't worry potassium phosphates in these drinks will prove to be harmless as long as you don't drop/raise pH beyond 0.2 ppm.

    I am a recovering organism all biologist that has failed at many attempts with discus, loaches, knife fishes, Amazonian stingrays, and Malaysian freshwater prawns. I am a trial and error learner (at my own expense lol), and have found these methods, if properly controlled, to be infallible.

    • Reply Dennis H. Jan 27,2015 1:44 pm

      Hi William,

      Thank you for taking the time to share your experiences. The community would certainly benefit from your trial and errors. :)


  16. Reply Bahaa Mar 17,2015 9:52 am

    Hi and thanx for this Amazing Article…how must can be add the driftwood in the tank to lower ph??
    best regards

  17. Reply Brialan Mar 26,2015 11:20 pm

    Thanks for the advice…I have a 55 gallon fresh water tank and have had horrible high ph problems….have lost numbers of fish. I have a fountain in my house that takes distilled water but gallons were so expensive to buy, I bought an RO system…Never knew RO water would lower the PH…

    I will start replacing the water in lots of 10 gallons over a few days and let you know…

    thanks for the suggestion.

Leave a Reply