Water Parameters: Everything about GH in Shrimp Tank

GH logo

General Hardness (GH or Total Hardness) is an important water parameter to shrimp keeping and breeding. Unfortunately, Carbonate Hardness (KH) and General Hardness (GH) are commonly confused.

General Hardness (GH) represents the overall concentration of salts (calcium, magnesium, iron, etc.) but does not identify which of these elements is/are the source of hardness. While Carbonate Hardness indicates the quantity of base present in water – bicarbonates, carbonates, phosphates, hydroxides, etc.

Water Hardness ChartWater high in calcium and magnesium is called “hard water” and water deficient in these minerals is called “soft water”.

In order to be successful in shrimp keeping hobby, it is absolutely important to understand what GH is, the difference between GH and KH and how these water parameters affect shrimp. I will try to keep it short and simple as I can. So bear with me a little bit.

Note: Carbonate Hardness is a confusing term because it does refer to hardness, but rather to the alkalinity (the ability of a solution to resist a pH change with an addition of an acid.) from the carbonates and bicarbonates. Other anions (such as hydroxide, borates, silicates, and phosphates) can contribute to the alkalinity. That is why some scientists believe that we should NEVER use the term “KH”; however, this is often referred to in aquarium literature.

Interesting: Usually, in freshwater, most of the cations are calcium and magnesium (In a 3:1 ratio) and most of the anions are carbonates. The levels for (GH) and (KH) will often be similar.

What is GH in Shrimp Tank? 

According to scientific definition, General Hardness is a measurement of total multivalent cations in the water. In practice and in simple words, it is the sum of the two most important elements, calcium, and magnesium in the water.

GH  ≈  [Ca] + [Mg]

Why do we use sign approximately equal ()?
Because, actually, the correct formula is (according to its definition – multivalent cations):

GH  =  [Ca] + [Mg] + [Sr] + [Ba] + [Fe] + [Mn] + [Al] + …

Well, now it looks very complicated. However, there is also another science definition. General Hardness (GH) is a combination of temporary and permanent hardness.  

General Hardness (GH) = Temporary Hardness (KH) + Permanent Hardness (NCH)

  • Temporary Hardness (Carbonate hardnessKH) is the amount of multivalent cations that are carbonates and bicarbonates. Carbonate hardness is named Temporary hardness because Ca and Mg carbonates precipitate as minerals upon heating. It is possible to lower permanent hardness by diluting it with softer water, ie. RO etc.
  • Permanent Hardness (Non-carbonate Hardness (NCH)) – Ca and Mg associated with sulfates, chlorides, or nitrates do not precipitate upon heating (therefore NCH is called Permanent hardness). Thus, raising permanent hardness can be done by adding calcium or magnesium sulphate.

General Hardness=emporary Hardness + Permanent Hardness

As GH is a combination of both temporary and permanent hardness, making any changes to these will affect the GH. Therefore, either boiling water or using a deioniser will lower GH. Adding any calcium or magnesium salt will raise GH. 

KH is higher than GH how so? 

Sometimes our tests show us that KH is higher than GH. How is it possible you can ask if GH = KH + NCH?

Well, we can blame KH tests.

It is not that they are wrong, of course not. Actually, the problem is that they are not measuring water hardness at all but alkalinity. In most cases, people use the terms “Carbonate hardness” and “Alkalinity” as synonyms. Well, actually, this is not right. These terms are very close but not the same. Let me explain.   

As we know, the KH indicates the quantity of:

  • Carbonates (HCO3) and
  • Bicarbonates (HCO3)2.

Both forms of carbonate are bound to metals, which normally would be calcium (Ca) and magnesium (Mg).

Important: The KH does not care what metal it is bound to. For example,

  • If bound to Ca or Mg, there is also a GH present.
  • If it is bound to K or Na there is a KH present, even if no GH components (Ca and Mg) are available.

Therefore, a large amount of NaHCO3 would raise the (KH) and not affect the (GH). A large amount of MgSO4 would raise the (GH) and not the (KH). That is why the real formula is:

GH = KH + NCH + PsH

 PsH is a Pseudo Hardness. It is the portion of the carbonate hardness that belongs to the monovalent cations (Na, K, ammonium). Unfortunately, KH tests measure them as well. This is how KH sometimes can be higher than GH.

Importance of GH in Shrimp Tank  

Calcium and magnesium are essential in the biological processes of our shrimp.

  1. Calcium Carbonate is crucial to the molting cycle of shrimp. It affects the hardening of the newly formed shell. According to some studies, the shrimp shell consists of the three main components Chitin (20-30 %), Proteins (30-40%), Calcium carbonate (30-50%).
  2. It is essential to maintaining precise levels of internal salts for the normal heart, muscle, and nerve function of the shrimp.
  3. Calcium Carbonate plays a huge role in breeding shrimp. It has a great effect on it. If the GH parameter in your tank does not match the proper level, your shrimp can lose eggs or stop breeding at all.
  4. These minerals also help in food digestion. They help the immune system to fight toxins and diseases in the body and can reduce overall stress in your shrimp.
  5. Calcium Carbonate can have profound effects on the level of stress and shrimp health, oxygen availability, and the toxicity of ammonia in a shrimp tank.

Important: Unfortunately, many shrimp keepers forget about Magnesium. Magnesium, actually, helps shrimp to absorb Calcium Carbonates. Ideally, we should have a ratio:

  • 4:1 (gH:Magnesium)
  • 3:1 (Calcium:Magnesium)

Without magnesium in your shrimp tank, your pets will not be able to use calcium and as a result, they will simply die.

You can read more about “Dwarf shrimp and Molting problems. The White Ring of Death” right here. 

Examples of GH and Types of Shrimp

Name Optimal GH Limits
Bamboo shrimp 6 – 8 1 – 15
Caridina cf. babaulti 6 – 8 4 – 14
Snowball shrimp 6 – 8 4 – 14
Crystal red shrimp 4 – 6 3 – 7
Ghost shrimp 5 – 8 3 – 15
Amano shrimp 7 – 8 5 – 15
Cherry Shrimp 6 – 8 4 – 14
Cardinal shrimp
6 – 8 4 – 12
Blue tiger shrimp 6 – 8 4 – 10
Blue bolt shrimp 3 – 6 3 – 8
Vampire shrimp 6 – 12 4 – 20

How to test your tank for GH 

API-test-GH-and-KHBasically, all test kits do it approximately the same way. I prefer test kits made by API (link to check the price on Amazon). This is a liquid test. The level of your PH is going to be measured by how many of these drops you put in the water.

  1. Take your test tube. Fill it up to the line. Now you want the meniscus of the water to be at the top of the line (the meniscus is sort of the tension on the surface).
    2. Then you add the solution one drop at a time. Every time you add a drop, you tilt it back and forth and you can see it immediately change the color.
    3. Count the drops (before it turns from orange to green).

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.  

How to Raise GH in Shrimp Tank  

Shrimp_Mineral1. Shrimp minerals GH/KH+ and GH+

They contain all minerals important for shrimps. Shrimp minerals re-mineralise e.g. RO water, rainwater, desalinated water etc., raising total hardness (°dGH) and carbonate hardness (KH) at a ratio of °dGH/KH: 1.0/0.5. Shrimp from habitats with a neutral pH do very well in water prepared with this mineral salt.

Shrimp minerals GH/KH+ and GH+ (link to check the price on Amazon).

Note: There are many other types of shrimp minerals on the market (Aqua Blue Wizard, Shirakura Liquid Minerals, Shrimp King Shrimp Minerals, Shrimplab Minerals, GlasGarten products etc). They are all good products and it is up to you to pick one.

Seachem Equilibrium2. Seachem Equilibrium

Seachem Equilibrium will raise your GH. It is primarily calcium sulfate and magnesium sulfate.

It is a good choice if you do not want to raise the KH or pH. However, you will have to add it every time you do a water change.

GH Booster3. GH Booster

You can also use GH booster (link to check the price on Amazon) or similar products, which normally contain calcium and magnesium sulphates. Gh Booster is a 1:3:3 mixture of Magnesium Sulfate ( MgSO4), Potassium Sulfate ( K2so4) and Calcium Sulfate (CaSO4). It raises General Hardness (GH) in soft water and RO water sources.

Crushed-coral-4. Crushed coral

Keep in mind that Crushed coral will raise not only your GH but also your KH. Another potential problem is that Crushed coral can raise the pH like crazy. Unlike specialized products, you do not know exactly how many you need to add. It is always guesswork and testing. The results can be very unpredictable if you are trying to work with precise numbers.

Wonder Shells5. Wonder Shells

They contain magnesium and calcium. Therefore, when Wonder shells dissolve, they release these elements into your aquarium and raise the GH.

Another great thing about Wonder shells is that they usually do not raise KH or pH. They aid in the maintenance of these parameters by neutralizing harmful acids, which result from organic decomposition. The Wonder Shells should be placed in an area with low water flow for best results. Do not place them in filters.

Do not add too many at once.

Cuttlebone 6. Cuttlebone

It is a good way to increase your GH. Cuttlebone dissolves slowly. It means that it is less likely can cause overdosing. At least, it will give you some time to react.
Note: For example, calcium blocks dissolve allot faster in the soft water potentially causing overdosing with calcium.

7.   Aragonite

This mineral is available as rocks or sand. Aragonite acts the same as crushed coral. It is made up almost entirely of calcium carbonate. Therefore, it releases both calcium and carbonate into your water.

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

How to lower GH in Shrimp Tank

Reverse osmosis unit and Distilled water1. Reverse Osmosis or Distilled water

 In order to lower GH in a shrimp tank, you will have to use RO/DI (check the price) or Distilled water. Reverse Osmosis or Distilled water is pure water. Basically, it is free from any bacteria, minerals, salts, and impurities. The TDS of this water is close to zero.

Use this water during small water changes to start lowering your GH. It would be a good idea to change a little every day or two and try to lower the GH by 2ppm.

Do not do any sudden changes! Be patient, acclimatize your shrimp or you will simply kill them.

Note: if you do not have Reverse Osmosis or Distilled water, either you can boil water or use a deionizer will lower GH. It is possible to remove bicarbonates of calcium and magnesium by simply boiling the water.

You can read more about “Best RO/DI systems for Shrimp tank” right here.

Peat moss2. Peat moss

It softens water and reduces its hardness (GH). It is advisable to aerate the water for 1-2 weeks in a bucket containing peat moss. Use an air pump to aerate it and approximately in 1-2 weeks, the water will be softer and more acidic. After that, use this aged water when making partial water changes in your tank.


Water quality parameters play an important role in shrimp life. The poor water quality is the leading cause of disease, stop feeding, retardation of growth, mortality, and breed failures. The maintenance of good water quality is essential for both survival and optimum growth of the shrimp.

15 thoughts on “Water Parameters: Everything about GH in Shrimp Tank

  1. My kh reads as 35.8 and my gh as 53.7 but from what I’ve read they should be higher for shrimp? I cannot find a good sight to tell me how to convert it to the 6-8 and so on. To know whether these are the correct perimeters or not. The tank is fully cycled ph being 6.8ppm ammonia being 0.ppm nitrite 0.ppm nitrate 0.ppm however I have also read that there are ph buffers such as alder cones that can be used to get the gh and kh at the correct levels for a shrimp tank. I have not found any definite answers for this, it would be much appreciated if you went over it! Or replied to this! This sight helped a bit but it’s not answering my main questions and I’ve run out of places to look.

    1. Hi Zane,
      Have you tried this converter? https://www.lenntech.com/calculators/hardness/hardness.htm
      Alder cones and Almond leaves will not help you much if you consider using them as the main source to buffer your water. Even driftwood cannot do this alone! You have to use them only as an additional way to keep the water acidic.
      Have you checked out my article – Water Parameters: Everything about pH in Shrimp Tank?
      I describe different ways of lowering down the pH.
      Best regards,

  2. Wow what great content now I know why I had a ton of snails in my tank and they started to die off little by little I remember seen the shells looking thin and full of holes, you can see the white in it then the shrimp stop breeding and much later all shrimps just vanished when they molted…. lack of Calcium! wow I be darn!

  3. Thank you for your excellent articles. I especially appreciated the reminder that nitrates will decrease pH and “use up” you alkalinity. One question: When topping off my tanks for evaporation should I add Shrimp Minerals to the make up water? I have been using DI water for this. I don’t want to increase my GH and KH too much by constantly adding too many minerals.

    1. Hi JaNaye Bryson,
      Thank you!
      Generally, I would not add shrimp minerals during top-offs. The point is that the minerals are still there, so if you add more minerals you will end up having even more in the tank.
      Nonetheless, you need to check your TDS first.
      Best regards,

  4. Hi there, thank you for this article. It really helps a lot. But I was wondering about the number in the optimal GH table, do you mean 6-8 drops based on API test kit?

    1. Hi Leonard,
      What do you mean by ‘drops’?
      This is a standard API pH test.
      If you are asking about higher ranger. Well, API also has a high range pH test for that.
      Best regards,

    2. Leonard,
      That table refers to the degrees of general hardness that each shrimp species prefers or can tolerate. A degree of hardness is about 18 ppm.

  5. Hello Michael! Are the gH values in your article expressed in ºdH? Thank you !

  6. Help me please, I’m having molting issues with my red cherries, my gh has jumped from 5/6 to 12 I’ve got it down to 8/9 by doing little water changes. I don’t have ro water please help me

    1. Hi Stella Mellor,
      Sorry to hear that.
      Why did it happen?
      If your tank is not large enough, I would simply buy some distilled water and used it in water changes.
      Best reagrds,

    2. Hello!
      I have very high gH (typically 12-17dgH) , but my ghost shrimps have been doing very well. The kH levels range from 4-7 dkH). My tank is mature and I always aclimate my shrimp. On the other hand, I’ve tested my tap water and both my gH (3-4 dgH) and kH (2-3 dkH) are very low to low respectively. The pH in my tank stays around 7.2-7.4. First, I’m wondering why they are doing so well with no failed molts. The snails definitely are doing well too! I’m assuming the calcium plays a major roll, but if calcium levels were very high there would be failed molts, right? Secondly, I can’t figure out what drives my kH and gH values so high in my tank since my tap water levels are low. My pH is also neutral (7) in my tap water. My tank parameter are:
      7.2 pH//0ppm ammonia//0ppm nitrites//0-5 nitrates.
      It’s a 10 gallon heavily planted tank (plus floating plants) with AquaNatural Diamond Black (blasting sand) and a few pieces of non-organic hardscape. I have a 30 gallon powerhead attached to a 20 gallon sponge filter and a 50 watt heater. I cycled the tank with fish food and seachem stability. The tank is a little over 4 months old. After cycling I was great about weekly 10-25% water changes. As it was fully maturing, I also had a cheap skimmer for the biofilm. It died a couple of months ago, and the biofilm has not noticeably returned (thank you floating plants!). As life got busier I started falling off of weekly water changes (it’s been a month-ish), but my parameters are great! I top off the tank with distilled water. The water is treater with Seachem products like: Prime, Stability, and Flourish. All are dosed appropriately with water changes and Flourish as needed. The substrate is treated with Root Tabs. I should also note when I was on top of water changes my gH and kH were in the same range.

      1. Hi Brooke Pittman,

        It’s possible that your Ghost shrimp have adapted to these conditions over time. 17 Gh is a bit high but this is not something extraordinary.

        As for your question, you mentioned that you use Seachem products, including Flourish, which contains calcium. It’s possible that the high levels of calcium in the water are contributing to the increased gH and kH levels. The AquaNatural Diamond Black sand and other hardscapes in your tank may have a high buffering capacity, meaning they can neutralize acidic compounds in the water and increase the pH. This could contribute to higher gH and kH levels.

        Have you checked your filter media?

        Best regards,

  7. Hey,

    I used the api test and my Gh was 14 and Kh was 1. Any suggestions? Thanks!

    1. Hi Leslie,
      In addition to calcium and magnesium, other minerals and elements may contribute to the overall GH value. In other words, Yes, a GH value of 14 and a KH value of 1 indicate that your water contains a significant amount of dissolved minerals besides calcium and magnesium.
      Thus, I would test your water somewhere else or changes your test kits to make sure they are correct.
      Best regards,

Leave a Reply

Your email address will not be published. Required fields are marked *

Recent Content