TDS – The Planted Aquarium Water Parameters

by Jun 20, 20209 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 TDS (Total Dissolved Solids) part of the planted aquarium water parameters.

Table of Contents

Importance of Knowing Good Water Parameters
Environmental Indicators
TDS (Total Dissolved Solids)
Too Much TDS
Too Low TDS
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.

Accumulated Wastes and Organic Debris

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 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) - You Are Here

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 Chlorine/Chloramine parts of determining good water parameters for our planted aquarium, we will now be discussing the TDS part, what are its 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, etc. We will also provide the acceptable water parameter ranges for different types of freshwater planted aquariums near the end of these articles.

Environmental Indicators

TDS (Total Dissolved Solids)

TDS is the measure of all dissolved organic and inorganic solid substances in your water. However, tests of this water parameter don’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.

This includes your GH, KH, Ammonia, Nitrite, Nitrate, dissolved organic wastes, etc., and everything you add to your planted aquarium (water conditioner, fertilizers, uneaten fish food, etc.).

Aquarium filters can only catch what comprises TSS (Total Suspended Solids), such as plant matter, fish wastes, detritus, etc.

Mulms and Organic Matter

So if you know that your water source is not adding up too much TDS, in my case, my purchased RO water is just adding up 20 ppm of TDS, you can approximate your TDS by knowing your GH, KH, Ammonia, Nitrite, Nitrate, fertilizers (fertilizers – in their simplest element form are not toxic to our faunas), etc. This will just leave you with dissolved organic wastes, water conditioners, uneaten fish food, etc., which you cannot measure directly, but you know they are there.

But if your water source like tap or deep-well water gives you about 500 ppm of TDS, you will not be able to know what comprises that 500 ppm of TDS, unknowns. Most especially if your tap water’s TDS is fluctuating wildly, this is unstable water. Add to the fact the unknowns you are dealing with. We don’t recommend using these water sources. Once you add that water to your tank, it will still increase due to the addition of the known substances mentioned above.

The advantage of a low TDS from your water source is you have fewer unknowns when you add that water to your tank during a water change. We know it will still increase because of the KH, GH, fertilizers, fish food, and how many fish we add to our tanks, but at least we know what we are adding.

Water Source and TDS

Let me give you an example computation of how you can approximate your TDS:

TDS = Water Source TDS + GH + KH + Ammonia + Nitrite + Nitrate + Fertilizers + Others

I have 20 ppm from my RO (the water refilling station showed their test probe to me)

I have a GH of 5 dH. Multiply it to 17.9 to get the ppm = 89.5

I have a KH of 3 dkH. Multiply it to 17.9 to get the ppm = 53.7

We all know by now that we should strive for zero Ammonia and Nitrite in our planted aquarium = 0 ppm.

My Nitrate at the time of this writing is about 20 ppm = 20 ppm.

If you can add all the fertilizer dosing you are adding to your tank = I got 38.226 ppm per week divided into twice dosing (micro – trace nutrients are negligible). These should gradually decrease when used by plants, but for this computation, I added them in one dose.

All of these give me a TDS of 221.426 ppm + Others (which is known but cannot be directly measured such as dissolved organic waste, maybe some uneaten fish food but I am not overfeeding and only feeding once a day, I don’t use any water conditioner, and my RO water is chlorine-free, they all come from inside the tank).

Rainbow Fish

I honestly admit, I only used a TDS meter a couple of times, borrowing from my good friend. As long as I am using RO water and not adding unknowns to my tank, I am very much comfortable. I keep mostly tetras (6 Cardinal Tetras and other Tetras) in my 35 gallons tank and some Platies and Minnows.

Cardinal Tetras are known to live in the wild with very low TDS, but they live happy and comfortable in my tank, swimming around, schooling, scavenging for food, and I already have 221 TDS + Other Substances (they will not breed, though). My Platies breed profusely in my tank too, at one point, I started with only 3 Platies, and they blow out to 40 plus. I know I was overstocked at that point, and I knew I had high TDS due to the accumulated wastes. I just gave away my adult Platies to my friends and co-hobbyists since then.

Cardinal Tetra Close Up
Platy Fish

I know at that point I may be having 500 ppm + of TDS due to overstocking. It is not deliberate, though. Fish won’t breed if they are not happy, and the environment is not conducive.

Now try that formula again and exchange my RO water with your tap water’s TDS, for example, 200 ppm of TDS, and add your KH, GH, Nitrates, Fertilizers, water conditioner, plus other substances coming from inside your tank. The point here is you are adding 200 ppm already of unknown substances in your tank from your tap water. You know part of that 200 ppm is chlorine or chloramine, and you will treat it with water conditioner, and it will also add to your TDS, but what about the rest?

Here in the northern parts of Metro Manila, Philippines, it is common to have 100-200 ppm of TDS from our tap water due to the water source comes from a reservoir. But here in the south, we usually have 500 to 600 TDS, which comes from Laguna de Bay. My deep-well water has 500 ppm + TDS due to being hard water (high GH), but I was using it before in my fish only tank for 2 years with no ill-effects. Just the mineral deposits in the glass are annoying.

I was Using Deep Well Water in Excess of 500 ppm TDS

Too Much TDS

You should be very much concerned about TDS if your fish are guaranteed from the wild and need a particular range of TDS by testing the water from its natural environment (they have not adapted into captivity yet or to our commercial water sources) or bred in captivity based from its natural environment.

I have known many hobbyists who just use their tap water (100-200 ppm) (conditioned first) with no issues with shrimps and other more sensitive fish. They don’t even test TDS at all.

Remember, this is just the baseline measurement. That 100-200 tap water TDS will still increase once added to the existing TDS in your tank and once you condition it to remove the chlorine, dose fertilizers, added some KH and GH boosters, and once you feed your fish, excrete wastes, and once detritus accumulated in your tank.

And I have also known many hobbyists that use RO water exclusively for their sensitive species. It is just a matter of keeping up with your maintenance schedules and tank husbandry for both water sources.

Bee Shrimp

Very high TDS in your water poses a danger to your fish/faunas wherein the low TDS water in the fish cells wants to equalize to the very high TDS water in your tank. The water in the fish cells attempts to flow out to a higher solution of dissolved solutes (very high TDS water) until the levels equalize.

This will affect the fish’s blood pH, digestive tract, and immune system, greatly affecting its health and risk of catching diseases or worse death.

Fish do absorb or lose water through their skin and gills in a process called Osmosis. Osmosis is the flow of water across semi-permeable membranes (for example, fish cells) from low concentration areas of dissolved things (solutes) to areas of high concentration. It serves to equalize the concentrations in the two areas.

For more in-depth discussion about Osmosis, please go here.

With that said, if you want to decrease the very high TDS (500 + ppm) of your tap or deep-well water in your location, you can do so by diluting it with RO/DI water or Distilled Water or switch to a water source that is known to have low baseline TDS level.

Jungle Style Planted Aquarium

Jungle Style Planted Aquarium. Image by zoosnow from Pixabay

Glowlight Tetra in a Planted Aquarium

Glowlight Tetra in a Planted Aquarium. Image by Cody Wu from Pixabay

Too Low TDS

Pure H2O can harm your faunas too (which we will explain further in the next article about safe water sources, go here). There is no harm in using a low TDS or zero TDS water source, just remineralize it first. It just means you have fewer unknowns with your water.

Zero final TDS in an established planted aquarium is actually impossible to achieve. Everything you add to your tank will add to your TDS.

With that said, if you are using RO water exclusively with 20 ppm or less TDS, it also means most of the good nutrients and minerals for the benefit of your plants and faunas are stripped away, and you have to remineralize it first (which will add to the TDS) before using in your planted aquarium.

How to Test

You can use a TDS Meter to measure the TDS level in your aquarium and the baseline TDS of your water source.

TDS Meter Water Parameters

TDS Meter Water Parameters

TDS Meter

TDS Meter

Update (9/19/2020): I recently acquired my very own TDS Meter last 7/13/2020, and it turns out the TDS of my tank water using RO/DI water is around 140-170 ppm compared to the 221 ppm we calculated above. My GH nowadays is 3 dH compared to 5 dH during our first calculation. I also cut back on fertilizers as I recently change my scape from heavily planted (somewhat Dutch) to less planted, a combination of Iwagumi and Hardscape Diorama Style.

The baseline TDS of my RO/DI water remains 16 to 20 ppm.

Update 4/14/2021: I tried to experiment since January 2021 to lower my KH from 3 to 1 and GH from 5 to 3 to achieve the 1 pH drop (30 ppm) concentration of dissolved CO2 and less than 100 TDS. Those are the only things that I changed. While I was able to achieve my goal, I notice that some of my Bucephalandra species suffered. Incomplete, deformed, lots of holes in the leaves manifested in them. 3 weeks ago, I started to gradually increase my KH and GH back to where I maintained them before (3 dKH and 5 dGH – 1-degree increase per water change). I notice immediately this week (4th week) improvements in my affected Bucephalandra species.

When you change a water parameter in your planted tank (whether you are experimenting, finding the balance, or trying to fix something), it may take weeks to months before you can notice any results. This hobby is not always about immediate results. You have to have a lot of patience.

My TDS Meter

So to summarize, in an established planted aquarium, we will recommend maintaining your water from 80 TDS on the lower end up to 300 TDS on the higher end to save you from all the headaches and anxieties. This is after you set up and added everything to your planted aquarium.

Personally, I keep my planted aquarium from 120 to 130 ppm TDS after and before water change respectively. Very narrow, but it is manageable because I am using RO/DI water with remineralization. The baseline TDS of my RO/DI nowadays is 26 to 27 ppm. I know what I put in my tank. 

Nature Aquarium Aquascaped by Bart Capundag Philippines

Nature Aquarium Aquascaped by Bart Capundag Philippines

It is the number that I settled with that works for my plants and fish. Every planted tank is unique and everyone should come up with a number that works for their setup. So we recommended a safe, manageable, and feasible range above.

You may also realize that TDS is not really a worthless measurement to take with regard to planted aquariums. It is one of the most important water parameters. It will affect the osmoregulation in your faunas and floras cells.

It can affect their health, immune system, ability to purge waste from their body, nutrient and water intake, stability, etc. 

Many issues with faunas that get attributed to large pH swings (you mess with your KH), or water hardness are actually caused by Osmotic shock. 

This is also true if you don’t drip acclimate your newly bought fish and didn’t research their preferred water parameters. It can cause the melting or wilting of aquatic plants too. 

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.


Last but not the least, TDS or Total Dissolved Solids is the measure of all dissolved organic and inorganic substances in our water. However, knowing or finding what comprises the TDS value is futile.

Therefore, TDSs importance is relative to what you are adding to your tank. Limestones add to KH and GH, GH/KH Boosters, fertilizers, fish food, water conditioners, Ammonia, Nitrite, Nitrates, etc. These are the substances that we know and can measure.

Those unknowns in the water, such as using unstable tap water (TDS is variable), you don’t know what substances are in that water and what comprises that TDS, so there is nothing to compare.

We also discussed the importance of TDS, its relation to Osmosis, and effects on our faunas due to very high TDS or very low TDS, and how to decrease or increase it.

Want to Explore More?

The Walstad Method for Aquariums

Most of the hobbyists in planted aquariums often use a substantial amount of technology/equipment to provide good lighting, filtration, CO2 injection, and fertilizer dosing in their aquascaped tanks. Some hobbyists choose to grow plants using very minimum technology as possible as they can and succeed in growing healthy and lush plants.

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.

Fancy Guppy

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.

Dutch Style Planted Aquariums

This style is characterized by many different assortments of plants and leaf types. Carefully planning and designing a multitude of textures, shapes, and plants’ colors is the main focus. It is much like the terrestrial plants that are displayed in flower gardens.

Internal Filters – Types of Planted Aquarium Filters

An internal filter is placed inside the tank and is totally submerged in water from the name itself. They were the first aquarium filters available for home aquariums. But with the dawn of aquascaping, these filters have lost their acclaim, but they still have their uses in planted aquariums.

Closing Remarks

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


  1. Lynne

    I’ve read a number of your posts on the water parameters needed for your aquarium and you really know your stuff, but for me it sounds so technical and complicated. I would love to have my own aquarium but I’m worried about taking on too much and not knowing how to care for it all on my own. I guess there would be professionals that can help me set everything up? Can you recommend anyone that you trust?

    • Lemuel Sacop

      Hello Lynne,

      Thanks for taking the time visiting and appreciating my articles. To be honest to you, I even didn’t know half of what I know now when I was starting with this hobby. It may seem a lot to consider with this hobby, but start slow, do your research, start with a good water parameters, you don’t even have to inject CO2 from the start, choose undemanding plants to lights and CO2, cycle your tank, get the hang of keeping a planted aquarium first, and everything will fall into place.

      It is a good start for you to find this website and every article in here is in sequence and will help you along the way. 

      You can choose to seek help with a professional aquascaper to set you up near your location, but you have to learn how to maintain it still. And a sensible aquascaper can help you with that. 

  2. Nathaniel

    Hello Lemuel – This is such an interesting science. Frankly, I hadn’t heard of planted aquariums prior to this reading. But it makes perfect sense for them to have the correct environment of the survival of the plants—especially the water. Thanks to this article, I will investigate this further and possibly get involved in owning a planted aquarium. Thanks for this opportunity!

    • Lemuel Sacop

      Hi Nathaniel,

      I really appreciate you visiting my website and takes interests into my article. I hope in some ways, I was able to help you in your decisions to keep a planted aquarium at home.

      There are a lot articles already in this website, all the essentials to help you on your first aquascape. Talk to you again soon.

  3. Trevor

    I am fascinated by your website and have been returning frequently as I am looking to install an aquarium in our new home. It seems to me knowing and understanding the right environmental standards are essential. It is very good to understand that filters for aquariums can only pick up what you have described.  This confirms to me that where we are living now, which has quite a lot of dust in the air, due to it being an industrial city, means it is not wise to buy our aquarium until we have moved to the countryside as we have planned. What I love about your site, is the detail.  It really is incredibly helpful and will, I am sure, help to make our first aquarium a real success. Do you have a specific recommendation for what is the best “starter” size aquarium? Or should we just “go for it” so to speak for the location and size we plan to fill in the house?  I look forward to your advice.

    • Lemuel Sacop

      Hello Trevor and thank you for visiting again. I am living in an urban city too but a bit far away from the main highway. Dust in the air should be the least of your concern, unless you are using rainwater for your water source. I got a lot of dust too in the surface of my water since my tank is in our terrace, and it is fine. But living in countryside and have a planted aquarium is what i’ve dreamed of too.

      As for the size of the aquarium for starters, it really depends on the location of your choosing, aquascaping style and how much budget can you allocate into your aquascape. How to choose a location and recommended sizes for your first planted aquarium were discussed in previous articles. Please use the menu to find it or use the magnifying glass.

      It is better to focus your money and effort in a small to medium aquarium 10 to 20 gallons long and get the hang of keeping a planted aquarium before venturing on very large tanks. You will be amazed on other’s creative works in the internet where it looks like it was done in a large tank, where in reality the scape was done using a 10-15 gallons tank. 

      An aquascaper can be called an illusionist where he/she can present a sense of depth, scale, and volume in a small tank.

  4. Cynthia

    I’ve never seen a living aquarium but now I’m fasinated. It seems like a huge undertaking but reading this me more confident that I might be able to do it. It sounds like it’s all about being alert, testing and adjusting. Trial and error. Do you have any advise for a newbie trying this for the first time? How costly is it to get started?

    • Lemuel Sacop

      Hello Cynthia,

      It may seem a lot, start slow, do your research by checking my website (everything are covered – navigate the site via the menu – every articles are in sequence so you won’t miss the important points), learn how to cycle your tank, start heavily planted, etc. When I started, I didn’t even know half of what I know now. Yes, there are lot of testing, adjusting to find the balance of your tank, but once you find it, you got to enjoy your little piece of nature at your very own home.

  5. reviewunbox

    Good One, You really did a fantastic job, Thanks for so much info

    Great article . Extremely helpful .


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