Water Parameters: Everything about pH in Shrimp Tank


pH in Shrimp tank

The power of hydrogen (pH) is one of the most critical water parameters for shrimp keeping and breeding. The optimum pH range depends on the shrimp species in the tank. Once you get this number, it is essential to stabilize the pH within this range.

pH is the measure of hydrogen ion concentration. The pH value in shrimp tanks is normally lowest in the early morning and highest in the afternoon. For the best water quality, the maximum pH fluctuation should not exceed 0.5. It is important to maintain a stable pH at a safe range because it affects the metabolism and other physiological processes of the shrimp.

It is most important that you keep your pH consistent. Shrimp are very sensitive invertebrates. Therefore, they do not like the changes very much. Of course, some shrimp species can be very hardy (Cherry shrimp, Snowball shrimp, Amano shrimp, even Ghost shrimp etc.) but it does not mean that they like it.

You can read more about “3 Most Hardy Dwarf Shrimp For Beginners” right here.

So, if you want to understand pH at a slightly deeper level, I will try to give you more of a background as to:

  1. What pH is.
  2. Why pH is important.
  3. How it affects our shrimp.
  4. Correlation between pH and kH.
  5. How to lower pH in a shrimp tank.
  6. How to increase pH in a shrimp tank.

What is pH

pH “potentia hydrogeni” or “pondus hydrogeni” is the logarithm of the hydrogen ion concentration in a solution, with the sign changed from positive to negative.
Did you understand it? What does it mean … in English?

In order to understand the principle, we have to start by talking about the water molecule first. Do not worry, I will try to keep it very short, simple and with pictures.

H2OSo, this is a water molecule H2O. The water molecule consists of:

  • 2 Hydrogen atoms (have a positive charge (H+)).
  • 1 Oxygen atom (partial negative charge on another side of the oxygen (O).

Oxygen is very greedy when it comes to electrons. It can pull the electrons towards the side with a negative charge. If we add another molecule of water, sometimes that attraction is so great that this hydrogen atom will actually become detached from the water molecule and it will become attached to another water molecule.  

Water molecule is trying to «steal» Hydrogen atomH3O and OHAs a result, we have:

  • Hydronium (H3O+). It is going to have a positive charge.
  • Hydroxide ion (OH-). It is going to have a negative charge.

Therefore, the pH stands for the power of Hydrogen. In other words, pH is the amount of Hydrogen (H+) but it could also be the amount of Hydronium (H3O+) or the amount of just free Hydrogen ion (OH-) inside the water. Actually, it really does not matter much because the result is the same.

How do we get 7 (neutral) pH

In regular distilled water, the chance of Hydronium (H3O+) or Hydrogen (H+) occurring is extremely rare. Basically, it is a 1 in 10,000,000 chance that we are going to have Hydronium (H3O+).

Now, let’s put this all in the equation of pH. Do not worry, we are almost done with science.

pH = −log10 [H+] or pH = −log10 [H3O+] 

Note: remember, for our calculations, H+ is also the same as the Hydronium (H3O+). Those are essentially the same thing. I will continue to describe it that way [H+] since the majority of people have been taught it that way.

Let’s replace H+ with 1 in 10,000,000 chance of getting it.
pH = −log10 [1 in 10,000,000] 

We take the negative log and write 1 in 10 million in scientific notation.
pH = −log10 [1 in 10-⁷] 

If you put these numbers in your calculator and if we take the negative log of 1 times 10 to the negative seventh, we get 7.

pH = 7 (neutral)

It means that the concentration of Hydrogen (H+) is going to be relatively small. Consider it as a balance. That is why we call it neutral. However, if we ever have a value greater than 7 it is going to be a Base (Alkaline) and if it is ever lower than that then it is going to be an Acid (Acidic).

pH scale

pH Fluctuations in Shrimp Tanks

The pH values are represented on a logarithmic scale ranging from 0 to 14. The lower we go on the scale the more Hydrogen ions will have in solution and vice versa.

Important: Logarithmic means that, each pH value is 10 times more acidic than the next value. For example, pH 7 is 10 times more alkaline than pH 6 and 100 times (10 times 10) more alkaline than pH 5! Just think about it. That as a lot of change. That is what stresses out our shrimp.

There are several biological processes, which are responsible for reducing or increasing the pH in our shrimp tanks all the time. For example:

  1. The nitrogen cycle

It is a vital biochemical process, which is responsible for the oxidation and detoxification of ammonia to nitrite and nitrite to nitrate. This process generates the release of 2 free protons and because it is happening 24/7 in high amounts it is responsible for lowering the pH.

  1. Photosynthesis

It takes place during the day when CO2 is removed (by plants) from the water column thus resulting in the consumption of Hydrogen ions (OH-). This is why the pH of a planted aquarium will gently increase throughout the day. In the nighttime, we have more CO2 present in the water. As a result, the lower your pH will become.

Read more about it in my article “CO2 in a Shrimp Tank”.

  1. Active Substrate

Active (buffered) substrate in the shrimp tank will also change the pH level by leaching the acidity.

It is important to understand that in our shrimp tanks the pH is always changing. Some shrimp species are extremely sensitive to pH and may require a narrower pH range to remain healthy. Our primal task is to keep it stable within a certain range. 

Examples of pH and Types of Shrimp

Name Optimal pH Limits
Bamboo shrimp 6.5 – 7.5 6.0 – 8.0
Caridina cf. babaulti 6.5 – 7.5 6.2 – 8.0
Snowball shrimp 7.0 – 7.5 6.0 – 8.0
Crystal red shrimp 6.6 – 6.9 6.2 – 7.2
Ghost shrimp 7.0 – 7.4 6.5 – 8.0
Amano shrimp 7.0 – 7.4 6.5 – 8.0
Cherry shrimp 7.0 – 7.5 6.0 – 8.0
Cardinal shrimp
7.8 – 8.2  7.3 – 8.5
Blue tiger shrimp 7.2 – 7.4 6.5 – 8.0
Blue bolt shrimp 6.0 – 6.8 5.5 – 7.2
Vampire shrimp 6.8 – 7.2 6.0 – 8.0

How does pH Affect Shrimp 

Sub-optimal pH has a number of adverse effects on our shrimp.

  1. If pH changes significantly, it can make shrimp shocked, weakened and stop eating.
  2. In high or low pH extends for a long time, it will make shrimp grow slowly, stunting growth and susceptible to diseases.
  3. It can cause stress, less survivals, low reproduction (or eggs loss) and leads to poor growth.

Signs of sub-optimal pH include:

  • increase mucus on the gill surfaces,
  • black gill disease,
  • damage to the eye lens,
  • abnormal swimming  behavior,
  • loose shell, soft shell, or too hard shell – molting problems for the shrimp.
  • irregularity in molt.

The low pH levels will cause the shell of shrimp to become soft. This is due to the shell of the shrimp being composed of calcium carbonate which reacts with acid. High pH may also increase the toxicity of other substances. For example, the toxicity of ammonia is ten times more severe at a pH of 8 than it is at pH 7. It is directly toxic to aquatic life when it appears in alkaline conditions. 

pH and kH Relation in Shrimp Tank

The aquarium pH is directly related to carbonate hardness (kH) levels in the aquarium. kH is the buffer that helps hold the pH stable. Therefore, if you are having a pH problem or your pH is dropping regularly you probably have a low to non-existent kH level. At the same time, high kH will not allow you to lower pH, when you need it.

So, it is a good idea to determine also your carbonate hardness (kH) level first. 

How to measure pH

pH Test & Adjuster KitAPI is one of the best pH test kits (link to check the price on Amazon). It has recommended itself very well and I prefer it. 

  1. Fill the test tube to the 5ml line.
  2. Add 3 drops of pH test solution, and then invert the test tube to mix the solution.
  3. Match the solution to the color card. 

Tip: If you have a hard time seeing the colors when testing the water, hold it against a white piece of paper.
Tip # 2: Make a list of all your measurements. You will be able to track all the changes in your tank to see if it maintaining its stability.  

Lower pH in Shrimp Tank 

I would like to start off by repeating that when dealing with pH issues it is very important not to raise or lower pH too fast in your shrimp tanks. You generally do not want to go more than about half a degree in any 12 to 24 hour period so if you have a long way to raise or lower your pH try to do it over a period of days.

Note: do not forget to acclimatize new shrimp before putting them in the tank. 

1. Reverse osmosis water
Reverse osmosis unitThe easiest and safest method is using an RO system in shrimp tanks. Reverse osmosis water is almost free of minerals and can be used to soften your tap water. You will have to use shrimp re-mineralizers during water changes. Remineralizers add all necessary minerals into the water that shrimp need to survive and thrive.


Distilled water2. Distilled water
Basically, for our goals, distilled water is almost the same as RO water. Highly-purified water (distilled, reverse-osmosis, other highly-filtered) has a TDS close to 0. You will have to use shrimp remineralizers as well.


substrates for plated tanks3. Substrate
You need a buffering substrate for that (ADA Amazonia aqua soil, Fluval Plant and Shrimp Stratum, Akadama-Bonsai soil, Shrimp king soil, Brightwell, etc). It will allow you to decrease your water pH for a long time (1-2 years).


Driftwood-4. Driftwood
It is a very cheap way to affect your pH. However, do not expect miracles. If your kH is high, driftwood will not help you much. Keep in mind, that driftwood releases tannins, which can turn your water like almost a tea color.


You can read more about it in my article “Driftwood in Shrimp tank”.

Cholla wood
Cholla wood

5. Cholla wood
Again, it has almost the same effect as driftwood. Check the price.

Note: In addition, your shrimp will love it! It is great to create mini caves for the shrimp to hide. When cholla wood breaks down a layer of biofilm forms on it. This biofilm just so happens to be one of your shrimp favorite foods.


Peat moss6. Peat
Technically, it is a form of chemical filtration because it serves almost the same purpose as carbon (However, carbon does not lower your pH). Peat brings down pH and hardness. It also adds tannins to your shrimp tank.

Sometimes, aquarists add peat moss as a layer underneath the substrate. It will help lower the pH for you but if you are new to shrimp keeping hobby, I would not advise doing that.
You can put some peat moss in a nylon bag and *add it in a filter or just hang it in the tank.

*Warning: peat moss will lower the pH of the water even faster than driftwood. That is why, for small tanks, it is not recommended to filter with peat, as it is hard to control.
Note: Make sure it is free of fertilizer and other chemicals.


API pH down7. Chemical (pH buffer)
This is a great way for beginners. Mix the pH buffer with tap water or to salt them up by using products to get parameters you want to. Link to check the price.

Tip: Measure your pH before you do a water change and after that.


lemon8. Lemon juice or vinegar
Add a few drops of lemon juice or vinegar. Then check the pH level. If it is still high, add a few more drops, and then check the pH again. Do this slowly so that your shrimp can adjust to the change in pH levels. You do not want to shock them.

Note: 1 mL of distilled white vinegar per gallon of tank water to initially reduce pH by about 0.3 units. 

Warning: Be very careful if you are adding vinegar to lower your pH. It causes CO2 to skyrocket in a very short period of time, causing bacteria bloom. In addition, it is not going to stay low. It is a short-term solution and you will have to keep adding it.

Lemon juice contains sugar.  Bacteria love sugar so you will have a bacterial bloom as well. It can lead to depletion of oxygen in your shrimp tank. Therefore, be very careful if you decide to use this method. Also, your shrimp tank should have good aeration.

All in all, personally, I would resort to this method only in case of emergency (too many side-effects).

9. Almond leaves, oak leaves etc.
Indian Almond Leaves Actually, any leaves will lower your pH because any decaying plant matter is going to have tannins. However, besides lowering pH, almond leaves are very beneficial for the shrimp. It is a nice source of extra food form them. In addition, almond leaves have antifungal and antibacterial properties. All shrimp really like it.

Keep in mind that leaves will not change pH if your kH is too high.

API CO2 Booster10. Carbon Dioxide (CO2)
One of the most used ways to lower the pH, although this is one of the least good ways to do so (in my opinion). Carbon Dioxide helps the plants to grow (fertilizer). It also bonds with the water creating carbonic acid. This acid lowers the pH but has no effect on hardness.

Note: Be very careful as overdoses of CO2 (link to check the price on Amazon) can cause major issues for the shrimp. In addition, it is quite expensive way to reduce pH.

11. Nitrates

Nitrates will lower the pH.  However, I seriously doubt that this method will suit anybody.

Increasing pH in Shrimp Tank 

1. Chemical.
pH up ChemicalsThis is an easy way of dealing with pH issues. However, there two types of products on the market.

  • Alkaline buffers will raise pH but will also raise your kH.
  • pH buffers will increase only pH (for example, such as “pH up”). Keep in mind that, increasing pH without dealing with kH is a kind of temporary fix. Nonetheless, if you do not need high kH it will be the better option.

Eco-Complete African Cichlid Substrate 2. Substrates
Just research the market, there are many options here. However, Eco-Complete African Cichlid Substrate is one the best for raising pH.


Crushed-coral-3. Crushed coral and Crushed oyster shells
Coral and shells have a very high concentration of calcium (carbonate). Due to the high amount of salt, it can be dangerous to the shrimp. The problems with using crushed coral you cannot really control the process. Therefore, you have to be very careful not to add too much.

4. Limestone
Limestone-based rock among other types will contain calcium carbonate which will work to raise the pH as well as GH in your tank. This is another natural method of raising pH and overall water hardness. 

Note: Be careful. Do not add too much. A lot of limestones can increase the pH up to 8.3 points!

5. Ash / Woodash
Ash can also increase the pH. However, it contains too much phosphor and phosphates. So, it is not recommended.

baking-soda6. Sodium Carbonate / Baking soda
Baking soda will raise the pH but it acts fast. The common recommendation is 1 teaspoon per 5 gallons. Due to the fact that baking soda is fast-acting, you should remove your shrimp or fish before adding it. The sudden change in pH levels will harm your shrimp.

7. Rocks
Rocks that contain calcium are used to increase the pH in freshwater tanks. In order to know that the rocks contain calcium, you can test it by putting a few drops of vinegar on the rock. If it starts to foam, the rock contains calcium.

I highly recommend reading my article “How to Supplement Shrimp and Snails with Calcium”.


The pH regulation in shrimp tanks is an important component in shrimp keeping hobby. The pH depends, among other things, on the CO² contained in the water and on the carbonate hardness (kH).

If your water parameters meet requirements, it reduces a lot of stress for your shrimp making them much less likely to get sick or die.

Depending on the species, however, some shrimp species require acidic or alkaline water to get breeding. Ideal for an aquarium with shrimps from the Sulawesi Lakes, the pH is between 7.5 and 8.5. By contrast, in the case of Neocaridina and various Caridina species, a pH of 6.5-7.5 pH, Red Bee shrimp should be kept at a pH of 6.2-6.8.


19 thoughts on “Water Parameters: Everything about pH in Shrimp Tank

  1. Thank you, I will practice it to optimize my ornamental shrimp farm

  2. Hi Michael,

    I’ve heard a lot of people suggest that to replace the substrate after 1-2 years because it cannot buffer the pH down to below 7. I can confirm that it is true because my tank uses Fluval Stratum and after 2 years my tank’s pH right now is 7.3. However, my CRS is still breeding like crazy and there are lots of baby shrimps in it. So, would you suggest that I replace the substrate or keep it as is right now?

    My tank info:
    Filter: sponge filter
    Substrate: Fluval Stratum
    Water: RO/DI Water remineralized with GH+

    Thank you

    1. Hi Daniel,

      Golden rule – If it’s not broken, don’t fix it!
      It is obvious that your shrimp got used to these water parameters and they like them. Aquarium is a complex eco-system. Therefore, do not change anything if you do not want to spoil everything.

      Best regards,

      1. Thank you Michael for a super fast response!

        Just one last question. In your experience, how often do you have to replace the active substrate if you are using RO/DI water with GH+? (Water’s pH is around 7) And if you have to replace the active substrate, what is the best method to do it without disrupting too much to the shrimps?

        Thanks again,


  3. Changing the substrate is a very debatable topic. Everybody does it their own way. I did it only a couple of times and every time I used a separate tank for that.
    Replacing all of the substrate at once is going to be a big hit to the nitrogen cycle. Therefore, you will have to setup a temporary tank for that.
    I know that some people advise changing the substrate partially. Well, personally, I think that it will be a total mess for weeks! So, it is better to do it all at once.
    Nonetheless, changing substrate should be the last resort. If your shrimp are OK, why bother?
    For more information, read my article “How to Change the Substrate in the Tank“.
    Best regards,

    1. Best comment that I’ve read in years. Thanks Michael!

  4. Hi there
    Enjoying reading everyone’s posts.
    I have a planted 200l tank with fluval stratum substrate. It’s been set up for a month. I started with a few snails and now have added ghost and red cherry shrimp. My ph keeps dropping from 6.4 to 6.1 ( Gh 75 ppm KH 40 ppm TDS 154). I have been bringing the ph back up to 6.4 by changing 10litres with tap water ph 7.2 . (It’s cycled ) I’m assuming it’s my substrate, but was wondering if it’s ok to leave it at 6.1 which is where it seems to want to stabilise? Or should I aim for a pH of 6.5 with buffers?
    Th either thing I noticed is that plant fertiliser significantly dropping my pH. I’ve stopped using it.
    But I’d like my plants to grow well. I’m using LCA shrimp safe in tiny doses..
    I guess my main question is what pH should the fluval stratum be buffering to…
    Kind regards

    1. Hi Louise Murray,

      Fluval stratum is not inert, it lowers pH. In my experience, it usually buffers right around 6.7 – 6.8 pH.
      Ghost and Cherry shrimp are one of the hardiest in the hobby. If your water parameters do not fluctuate, I will no be surprised if they adopt to even such low pH.
      Although there is a chance that Cherries will not breed much.

      Best regards,

    2. Hi Michael,

      thank you for your articles I really enjoy reading them all.
      Please, is it good idea to install a ph controller if you use CO2 gas?

      thank you very much


      1. Hi Veronika,
        I would definitely recommend it.
        pH is the most important water parameter when we are talking about shrimp keeping.
        Best regards,

  5. Hi Michael
    I was using tap water in a Planted Tank with CO2 and Fluval stratum but my Caridina were gradually dying off. Neocaridina were going OK
    Parameters were;
    Tank 70L, Fluval Stratum, heavily planted
    Ph 7.3, 6.7 with CO2 running
    Gh 5, TDS 350

    I changed to RO with liquid GH+ and have gradually attempted to reduce my TDS

    Current parameters;
    Ph 6.0 pre-CO2, presumably lower with CO2 running
    GH 5, TDS 200
    ammonia 0, Nitrite 0, Nitrate 0 (floating plants)
    However my Caridina have died and I have lost a lot of the Neocaridina

    Do you think the low Ph would be the issue, and if what could be the cause and how best to fix it?

    Cheers Greg Driver

    1. Hi Greg Driver,
      Sorry to hear that.
      It is never recommended to keep Neocaridina and Caridina species together because they require different water parameters (with some exceptions for a few species).
      Your Neos were OK because those water parameters are good for them.
      They are hardy enough to live in tap water with high TDS.
      Unfortunately, it cannot be said the same about Caridinas, that is why they suffered.
      However, once you started ‘optimizing’ your water parameters for Caridinas, you created unexcepted parameters for Neocaridinas.
      In addition, your pH is on the lower end. With CO2 running it most likely drops to around 5.5.
      All these fluctuations are not good for the shrimp, especially, when they are not in the recommended pH range!
      So, I am pretty much sure that pH is the main reason why they died.
      Best regards,

  6. Hi Michael. I just got some Blue dream neo shrimp but for some reason even after I acclimated them, 3 died. I’m not sure if it’s because of stress or different parameters. Ph is 7.4, gh is 8, kh is 8, temp is 73.

    1. Hi Greg,
      Sorry to hear that.
      Although drip acclimation is the safest way to introduce shrimp into a new environment (we can’t just plop and drop them), we can still be problems that are beyond out abilities.
      For example, too much shipment stress, too weak speciments, long period of starvation, etc. In addition, the first month is the most important in shrimp keeping. This is the red zone – even if you do everything right – your shrimp can still die because of previous stress, underfeeding, etc. All these things have an accumulative effect. Unfortunately, you can’t do anything about it.
      In addition, ideally, you need to know water parameters they were kept in.

      Best regards,

  7. My tap has a ridiculously low gh & ph (6.2) have contemplated added a small pouch of crushed coral in the canister to bring it up a bit.

    I’m also looking at making my planted 10gal a species tank for these blues since they have some of the worst requirements.

    1. Hi Justin,
      Crushed corals should help you out but it can be really hard to control the changes.
      Be careful and check your pH to avoid sudden changes.
      Best regards,

  8. Hi Justin,
    My Q. is how to stable pH ?
    I have a water storage unit for shrimp breeding tanks with an RO system.
    an RO water output parameters are:-
    TDS :- 50-60
    GH :- 0-1
    KH :- 0-1
    pH :- 6.8
    I have Cardinia & Neo Cardinia shrimps. When I add shrimp minerals like GH/KH in shrimp tanks everything is going changes and gives the perfect environment to shrimp except pH. My pH is going high day by day and reaching 7.5 to 8 & because of it, I have to change the water very frequently & shrimps are getting stressed. Sometimes few died too.

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