pH – The Planted Aquarium Water Parameters

by Jun 20, 20206 comments

Every healthy ecosystem requires a balanced environment, including the environment we lived in. Just like we humans and land animals cannot survive breathing polluted air or drinking contaminated water, aquatic life (faunas and plants) will have a difficult time living in sub-optimal water. Of all the balanced factors that go into a successful planted aquarium – the filtration, lighting, CO2 injection, fertilization, substrate – I would insist that the quality of the water used in our planted aquariums may be the most important. In this article, we will be discussing the environmental indicators pH part of the planted aquarium water parameters.

Table of Contents

Water Parameters
Environmental Indicators
Too Alkaline?
Ways to Decrease
Too Acidic?
Ways to Increase
How to Test?
Stressing This Out Again
Closing Remarks

Weekly water parameters tests from the beginning weeks to months of your planted aquarium are critical to making sure that your parameters are in check, don’t let others say otherwise. The way co-hobbyists talk about good water parameters can be confusing at times. Add that to the fact that you may have different water sources and parameters due to your differing location/city, and you may not be able to replicate what works for him/her. That is why every planted aquarium is unique, and you have to find the balance of what you’ve got in hand.

Water Parameter pH

Water Parameter pH

Knowing what makes ‘good water’ for your planted aquarium is critical for maintaining a healthy environment for your fish and plants. It will help us understand the intricacies of a planted aquarium and will arm you with valuable insights on what to do if you notice any problems. Knowing good water parameters even helped me think outside the box, formulate theories, and tested it to see what works and what doesn’t, which I will explain later below.

The planted aquarium water parameters can be further broken down into categories, namely:

Water Parameter pH

pH - You Are Here

pH is the measure of the acidity and basicity of your water. The range goes from 0 to 14, with 7 as neutral. pH lower than 7 indicate acidity, and pH greater than 7 indicate basic or alkaline water. Like the Richter scale used to measure earthquakes, the pH scale is logarithmic, so a pH of 5.5 is ten times more acidic than a pH of 6.5.



We will not over-complicate this. Temperature is just the measure of how much heat is in the water, hot or cold. But too big fluctuating temperatures will have bad effects on your faunas and plants in our planted aquarium.

Gas Bubbles Carbon Dioxide Laacher Lake Germany

Dissolved Carbon Dioxide

Carbon dioxide is naturally produced in our planted aquariums, even if you are not injecting CO2. When beneficial bacteria break down the wastes in our tank, and when faunas respire, CO2 is produced. While carbon dioxide accumulates during lights off, it will quickly be depleted by your plants at the start of lights on.

Sparrow Drinking in Faucet

Chlorine and Chloramine

If you are sourcing your aquarium water from a commercial water system (tap water), water should be treated to ensure it is safe for human consumption. The water is cleaned and filtered, then add chemicals to prevent anything harmful from developing in the water while traversing the pipes leading to our homes.

Accumulated Wastes and Organic Debris

TDS (Total Dissolved Solids)

TDS is the measure of all dissolved organic and inorganic solid substances in your water. However, the test of this water parameter doesn’t say what comprises your TDS. It measures the total of all molecular, ionized, and any microscopic substances in our water that cannot be caught by your filtration.

After we discussed the Nutrients and Minerals parts of determining good water parameters for our planted aquarium, we will now be discussing the Environmental Indicators part, what are their effects, what happens if you have too much or too low, what can you do if you have too much or too low, how to test them, etc. We will also provide the acceptable water parameter ranges for different types of freshwater planted aquariums near the end of these articles. We will start the Environmental Indicators part with the pH water parameter.

Environmental Indicators


pH is the measure of the acidity and basicity of your water. The range goes from 0 to 14, with 7 as neutral. pH lower than 7 indicate acidity, and pH greater than 7 indicate basic or alkaline water. Like the Richter scale used to measure earthquakes, the pH scale is logarithmic, so a pH of 5.5 is ten times more acidic than a pH of 6.5.

In nature, pH is a general environmental indicator that is the collective result of many different chemicals and compounds (largely by KH, which we covered in-depth in the previous article). This means that replicating the stableness of KH/pH of a particular natural environment to our enclosed system (planted aquariums) is not easy because there are a lot of factors that result in that stable pH.

Creek and Forest

As I said in the previous article about KH, it is not the pH swings that result from natural acids produced in our fish tanks or injecting CO2 in our planted aquariums that harms our faunas. It is when you mess with your KH that results in large pH swings in a very short amount of time that is the culprit.

Always strive for a stable KH. Acids will eat away at your KH first before significantly affecting your pH, but remember KH depletes too in our planted aquariums, and it needs to be replenished. In nature, KH is constantly being replenished. Still, even in a zero KH natural environment, pH swings wildly from area to area (from slow-moving water that is very acidic to moderately moving (acidic) to fairly fast-moving (a little acidic to neutral to basic) and sometimes back to slow-moving again, but faunas are not affected.

Stream and Forest

Too Alkaline?

High or very high pH is usually the result of high KH, which may not be suitable for the faunas you want to keep. So research first about the needs of the particular fish.

To lower your pH, you first have to lower your KH. While increasing KH is an easy task and easy to screw up too (that is why the friendly reminder to slow down), lowering KH is somewhat difficult.

Ways to Decrease:

We already discussed the many ways to decrease pH by decreasing KH first. Go here.

Nature Style Aquascaped by Algine Francis de Ramos Philippines

Nature Style Aquascaped by Algine Francis de Ramos Philippines

Too Acidic?

So you found out after testing that your water pH is acidic or very acidic for your Cichlids (for example) that you are planning to keep, and you want to raise it to alkaline? But to increase your pH, you have to increase your KH first. As always, take it slow when using commercial buffers and baking soda, don’t try to increase your KH from 0 to 5 in one go. For example, this will shoot your pH from acidic to alkaline (6.0 to 8.0 + which means it’s 100x more alkaline than before in a very short amount of time, remember pH scale is logarithmic – 2 points swing – x10 x10), your faunas will not have any chance to adapt). Just go with increments of 1 dKH every 2-3 days and monitor your KH, GH, pH, and your faunas. If possible, don’t do this with your faunas in your tank, do this from the start-up.

Ways to Increase:

We already discussed the many ways to increase pH by increasing KH first. Go here.

Hardscape Diorama Style Bonsai Aquascaped by Aristotle Quintana Comboy

Hardscape Diorama Style Bonsai Aquascaped by Aristotle Quintana Comboy Philippines

How to Test?

I personally use the API Freshwater Master Test Kit, which includes pH and High Range pH Tests. For my needs, it is cost-effective and accurate enough. Color charts can be somewhat subjective, so I advise you to compare the mixture color to the color chart under the light of your planted aquarium (and be honest to yourself).

pH Test
High Range pH Test

Stressing This Out Again

I want to stress again. Every planted aquarium is unique. What worked for others may or may not work for you. We all have a differing degree of planting, tank sizes, water parameters, water sources, stocking, maintenance schedules, lighting (intensity and spectrum), injecting co2 or not, filtration, aeration, substrates, even external factors like extreme weather conditions and ambient temperatures, etc. it is up for the hobbyist to find the balance of all these factors.

You can also ask for help from others who are willing to help and have the experience. A sensible co-hobbyist will ask some questions first before jumping to conclusions (even if he had the same symptoms before) like what is your water parameters, how old is your tank, did you perform any tank cycling, or do you even know what tank cycling is, what did you changed before the problem happens, what is the size of your tank, filtration used, the substrate used, how is your stocking, your feeding schedule, and maintenance, to name a few.

From your answers, he may be able to create a hypothesis and test it. He may ask additional questions to prove his theory further until you both reach a conclusion and resolve the problem.


Now that we discussed the pH water parameter and its importance with our planted aquariums, pH is the measure of your water’s acidity and basicity. The range goes from 0 to 14, with 7 as neutral. pH lower than 7 indicate acidity, and pH greater than 7 indicate basic or alkaline water.

We also learned that pH is directly proportional to KH, and if you want to increase or decrease your pH, you have to increase or decrease your KH first. But in doing so, we also have to be careful as messing with your KH, rushing or overdosing, will cause too wide pH swings in a very short amount of time, which can kill our faunas.

Some fish or shrimps species may require a very narrow pH range, so please research first on the faunas that you want to keep.

Want to Explore More?

Planted Aquarium for Beginners

Here on this page, I will walk you through setting up your first planted aquarium for beginners. Starting up a planted aquarium can be difficult for a beginner with all the conflicting information and “one size fits all” advice on the internet. Or, the beginner hobbyist happened to visit a local LFS (Local Fish Stores) and has been misinformed to buy this or that which are not essential, compatible, or too expensive for the planted aquarium he/she had in mind as a beginner.

Betta Fish

Modified Traditional Method – How to Cycle a Planted Aquarium

The fastest method of cycling our planted aquarium works if you have an old established tank or a friend’s tank, but what if you don’t have any and are starting from scratch? The traditional method of cycling our tank, fish-in cycling, involves adding a few hardy fish to jumpstart the Nitrogen Cycle.

Hardscape Diorama Style

The Hardscape Diorama Style is still a subset of the Nature Style. The only differences are emphasizing using a lot of hardscapes and building complex nature-like structures such as forest, caves, bonsai trees, canyons, or even fantasy worlds (think Avatar 2009 movie). Building just the structures takes days, weeks, or even a month before even planting.

Repurposed Furniture Stands by Ayong Go Philippines

Where to Place a Planted Aquarium at Home

Planted aquariums require less work to maintain (once you find the balance of everything) but need more work to set up for the first time. So we need to plan for it properly. Most importantly, we need to consider the ideal location of the tank at our home. So in this article, I will walk you through all the considerations on deciding where to place a planted aquarium at home. After this, we will determine the dimensions of the tank that can fit in your desired location.

Sump Filters – Types of Planted Aquarium Filters

Think about a trickle filter as vertical filtration stages and a sump filter as a horizontal one by utilizing chambers separated by baffles to route the water horizontally. The main takeaway here is that the filter media are always wet/submerged in water as opposed to a trickle filter.

Riparium Aquarium Style

A Riparium is a type of Vivarium that typically depicts an environment where water meets land (riverbanks, streambanks, the shoreline of marshes and swamps or lakes), but it does have minimal to no land parts, unlike a Paludarium (which provides significant land parts). In other words, you are replicating the shallow parts of these natural bodies of water.

Closing Remarks

I hope you enjoyed this article. If you have additional questions or want to share your experiences with the pH parameter in your planted aquarium, please leave a comment below. Next, we will be discussing the Temperature Parameter for our planted aquariums.


  1. Amy

    I am very new to the aquarium world so I am finding your articles so helpful. I had actually never even heard of KH levels so I definitely need to research this further so thank you for drawing this to my attention because I’m beginning to understand these need to right in order to get my PH levels right,

    I’m absolutely going to get API testing kit, I have a relatively small aquarium W120 x D40 x H71.5cm, what filtration system would you advise?

    • Lemuel Sacop

      Hi Amy,

      Thank you that you find this article helpful. We discussed KH and GH in depth prior to this article.

      If the dimensions you provided have no typo, I wouldn’t call it relatively a small aquarium, its 90 gallons. I only have 35 gallons currently and you have more than twice as mine. As for filtration, we recommend x5 to x10 turnover rate for your 90 gallons, this means you need 450 to 900 gallons per hour. 

      You can opt for one canister filter like the sunsun 304b, 525 gallons per hour turnover rate, and just deploy mini submersible pumps or wave makers to help circulate the water across the whole tank. Or you can choose to use two canister filters for even distribution and circulation such as two Sun sun 303bs 370 gphx2, that’s 740 gph total. 

  2. Anthony Beatrice

    A lot was said in a small amount of space; it was informational though.  I’m still not sure what kh is, but I will certainly look into it if I”m going to get some fish.  I always thought you just change the ph, I never realized there was a previous step.  You’re not going to have much luck with fish if you don’t listen to what’s in your post.  It seems like when you use today’s water, it would be acidic, but it’s not the same everywhere.  There are some places you’d have to think of lowering the kh and ph.  Thanks for this post, it’s a good source of information.

    • Lemuel Sacop

      Hi Anthony,

      Thank you for visiting my site and appreciating my article. Yes, in order to change your pH up or down, it should be the KH that needs to be changed first. That is a common misconception that you can just change your pH easily without regards to KH.

      KH and GH are discussed thoroughly in this article.

    • Michael Christmann

      Water parameters, environmental indicators, pH, KH, GH…..and so much more valuable information that you have provided in this article. I knew that having an aquarium required some work, but I honestly had no idea how many things there were to be considered. Thank you for sharing so much important information in this article.

      • Lemuel Sacop

        Hello Michael,

        Thanks for visiting my website and I hope in some ways, I was able to help you in your decision in keeping a planted aquarium at your very own home. It looks like it has a lot to absorb but once you get the hang of everything, you get to enjoy your creative work and your little piece of nature.


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