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Alkalinity vs Basicity? – A Perfect Balance in Pond water

Water is an inevitable component of a pond. It has different pH levels in different places. Like, in seawater, there is about an 8.1 pH level, and in drinking water, there is almost 6.5-8.5 pH.  A pH is a measurement of whether the water is acidic or basic. For a small fish pond, there must be a pH closely 6.5- 9.0. 

Now, which form of water will be perfect for a pond environment?

Both alkalinity and basicity are important in different stages. Highly acidic water can be harmful to fish and aquatic plants. As well, low alkalinity is also bad for pond water.

You need to know the basic differences between alkalinity and basicity to get an idea about your pond’s water state. So let’s get some differences with examples to understand the water level situation in your pond.

What is Alkalinity?

Alkalinity is water’s capacity to resist acidic changes in pH or neutralize the acidic level and also measures the total concentration of bases in the water. For pond water, at least 20 ppm alkalinity is required for more production in water.

More alkalinity is better than low alkalinity. 

If you are having a garden pond then go for an alkalinity test. Know whether your pond’s water is getting alkaline or basic.

If the pH level goes down more than 6.5 or raises more than 9.0, it will be harmful to fish. It is to say that this pH level fluctuates for alkalinity and basicity.

What is Basicity?

The capacity of acid to react with a base is measured by the number of hydrogen atoms that can be replaced by a base in acid to neutralize the acidic form.

Whenever your pond’s water will be acidic, you will need to add some base to make the water neutralize or the required pH for the survival of fish. High acidic water can burn the skin of fishes. Just to avoid the acidic form of water, basicity is needed. 

A Balanced  Quality of a Pond Water: Alkalinity vs Basicity

The underwater biological system controls the concentration of carbon-di-oxide. Carbon-di-oxide plays a significant role in the photosynthesis process underwater. Where photosynthesis exceeds respiration so pH level increases there as carbon dioxide(CO2) extracts from water.

During Sunlight, aquatic plants resume photosynthesis and remove carbon dioxide from water, pH rises again in the water. On the other side, pH falls down at night because the photosynthesis process remains stopped. In most cases, the pH level remains in a tolerable state for all aquatic lives.

Below pH scale can help you to know the range of acidic and basic forms of water.

Alkalinity vs Basicity

Balanced water quality will surely enhance your production. Aquatic plants and fishes have a certain level of tolerability in pH. A pond’s water should have a standard value to ensure the survival of all aquatic life. Let’s see the standard values for pond water –

Table 1 is the standard measure for pond water.

ParametersStandard Values
Oxygen (Dissolve)> 4.0 mg/l
pH6.5- 8.5
Carbon dioxide(CO2)< 10 ppm
Ammonia 0- 0.5 ppm
Alkalinity50-300 ppm
BOD< 50 mg/l
Hardness40-400 ppm

By understanding this table you can easily go for a test and let your pond water be neutralized or fish tolerable.

According to this table 1, your pond water must have dissolved oxygen more than 4.0 mg/l. Lower rates than this may affect the fish and plants’ lives.

Do’s and Don’ts

High pH or low pH can affect your pond production. Both can be dangerous for aquatic life in a pond. But the matter of concern is pH can be balanced if it is gone for high or low.


Whenever you will notice that water’s pH is low or high, instead of being panicked, you must follow the doings.

Control High Level of pH

 Does your pond have high pH? Don’t worry. It can be solved. Simply, You can control your pH levels in the pond. Just add Sodium Bi-Sulphates.

How much sodium bisulfate is needed to add to the water?

Here is an ideal measurement for adding sodium bisulfate to your pond water. A 500-gallon pond will need nearby 0.75 ounces or 1 tablespoon of sodium bisulfate. But you should add it slowly. Check the pH level frequently and pour the sodium bisulfate until the pH level gets to a stable level.

Control Low Level of pH

After testing with a pH test kit, if you noticed that your pond is having low pH, then don’t need to be tensed. Add lime water to your pond to increase alkalinity. Low levels of pH can also affect the productivity of fish. In this case, you will need to add grounded agricultural lime.

Also, you can add baking soda to the water to make a stable pH level. Pour it slowly and check it after every six(6) hours later to find a stable pH level. For an ideal lime amount, you can get help from a nearby local extension office. They will suggest you according to your pond size and pH level. Besides these, you need to clean your water regularly.

Things You Will Need
  • pH test stripe
  •  Water tet kit
  • Limestone/ Lime water
  • Sodium bisulfate
  • Baking soda
  • A boat( If necessary)


 The acidic or basic, whatever the conditions are, should remain at a balanced level. For this, you should follow a regular basis of clean-up.

The routine you should follow-

  • Overstocking
  • Overfeeding
  • Over planting
  • Irregular debris clean-up


As you will be working with some chemical substances like lime, sodium bisulfate, and baking soda so you must keep some cautions like-

  • Safety glasses
  • Hand gloves
  • Burnol

Final Verdict

After understanding the water condition, you will be able to take a precise decision about your pond. Pond water can be either acidic or basic. Whichever the form is, you need to make it at a neutral level for the high production of your fish. Keep remembering that, pond size does matter while pouring any kind of substance. This article might help you to control the pH level of your pond.


Does high alkalinity mean basic?

If pH is more than 7, then it is alkaline or basic.

Do Alkalinity and basicity are same?

No, theoretically not the same.

Is baking soda acidic or basic?

 It is an alkaline substance.

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