How To Manage High pH Problems In Fresh Water Ponds.

High pH problems In fresh water ponds and how to manage it.

I welcome you to Solutions4Success blog where we talk about things aquaculture and fish farming.

Today, we will be talking about high pH problems and how to manage it. But before we dive deep into our topic, first Let’s try to understand what pH is and what it is used for.

What is pH:

It is level of hydrogen ion concentration in an aqueous or other liquid solutions. The term "pH" is of German origin, and is derived from p representing German Potenz ‘power’ + H2, the symbol for hydrogen.

It is the negative logarithm of hydrogen ion concentration in an aqueous solution, in layman term; it is a scale to measure the acidity or alkalinity of an aqueous solution, and it was introduced by Søren Sørensen in the year 1909.

High pH problems:

It is good that we talk a little about pH because the aquatic ecosystem is highly dependent on pH, hence pH is one of the most critical factors that determine maximum profitability in all aquaculture/fish farming operations.

Now back to our original discussion on high pH problem but before we begin I would like to ask; does anyone know that it is possible for pH to become so high that it becomes a problem that is worth discoursing? Or better still how does high pH affect the average fish farmer like you reading this blog post? Well! Let's see.

High pH problem is usually common in water with poor buffering capacity, and low hardness but it is more predominant in fertilized water systems otherwise known as green water. It is well known that fertilized or green water containing natural feed items such as phytoplankton, zooplankton, and other benthic organism is very good for fish culture and some argue that the benefit of green water far surpasses that of plain water in fish culture, especially in catfish cultivation because it contains natural feed items, thus, leading to the reduction in artificial dry feed being fed to the fish and looking at it from the economic stand point; it puts money back into the pocket of the fish farmer, given that you only feed less and the growth and survival rate in such system is good.

The term, "green water” is given to water saturated with algae i.e. phytoplankton. The water gets its green color from the algae continued in it and such system is usually saturated with oxygen given the chemical reaction of the green pigments of the phytoplankton called chlorophyll; which chemically converts C02 from the water in the presence of sunlight to produce food (simple sugar) for the plant and gives off oxygen as a by product. It is this process that cause rise in pH.

Two types of organisms live in water, aerobic and anaerobic organisms.

Aerobic organism carryout respiration which uses oxygen and produce C02 as by products, while anaerobic organisms e.g. phytoplankton. Carryout photosynthesis which uses C02 from the water and produce oxygen as byproducts. Phytoplankton is able to switch from aerobic to anaerobic mode given certain stimuli in the environment.

During daylight photosynthetic activity in pond water is high and surpasses the respiratory activity in the water, as a result there is rapid removal of C02 from the water due to the anaerobic process of algae which increase the pH of pond water. In water with low buffering capacity the pH could rise to a very dangerous level which can lead to massive fish kill but in water with good buffering capacity the buffer is able to supply the C02 needed for photosynthesis and still maintain the pond pH at a suitable level. High pH problem occur in ponds during the day, when the sun is at its peak i.e. from 10am to 4pm, and this drastic rise in pH is undesirable for successful fish culture.

High pH problems could occur in the following systems:

1. Water with poor buffering capacity

2. Water with high alkalinity but low hardness

3. Fertilized water with high algae.

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How to manage high pH in fresh water ponds:

Balance hardness with total alkalinity.

One thing we have to understand about water especially groundwater is that it is never pure and it comes with a lot of dissolved salts mainly calcium, magnesium, sodium, bicarbonate, sulfate, chloride, and nitrate. Water that contains the above minerals especially does that contain high calcium are said to be hard.

 The salts mostly used by farmers to buffer water are calcium carbonate (lime), sodium bicarbonate (baking soda) and sodium carbonate (soda ash) all this put together gives us the total dissolved solids (TDS), while the combination of all minerals found in water plus the dissolved buffering salt gives us the total alkalinity.

When the TDS or hardness is not balanced with the total alkalinity high pH will result, hence the first step in managing high pH problems is by balancing the total alkalinity with total hardness which is the TDS.

Add Alum To Pond:

Another thing to know is that high pH is a result of the increase of base or alkaline in water, and the reduction of acids. What this means is that another way of reducing the pH of a fresh water pond is by adding an acid. Yes I said it; to reduce your pond pH when it is high you can add acid. While this solutions is only temporary an emergency treatment that quickly reduces high pH is the application of aluminum sulfate or alum. This is a safe and relatively inexpensive salt that reacts in water to form an acid. High pH can also be caused by increased algae blom, in this case alum flocculates and removes algae by sedimentation, thus decreasing the algal biomass and reducing photosynthesis. Alum may also help to reduce pH indirectly by removing phosphorus which is an important nutrient for plant growth.

Alum has a short-lived effect hence it needs to be applied more than once until algae decreases.  A precise reduction of pH through the addition of alum is difficult to calculate because the reaction is influenced by a number of conditions in the pond, especially the water’s total alkalinity. Overusing alum can cause a dramatic decrease in pH to levels more dangerous than the original high pH problem, so to be on a safer side use small amounts of alum.

Add carbon dioxide To Pond:

Another method that is safe, longer lasting and actually works to reduce high pH in fresh water ponds is to add carbon dioxide, which reacts with water to form an acid. Carbon dioxide levels can be increased by adding organic matter such as cracked corn, soybean meal or leaves to ponds. As organic matter decays, it releases carbon dioxide. This method does not reduce pH immediately, but it is a safe and relatively dependable way to reduce high pH rather quickly. Generally, applying about 5 kg per acre daily for about 1 week should prevent pH from rising to high levels. This amount would be in addition to any daily application of organic fertilizer that already had been planned. The total daily application of organic matter should not exceed 18 kg per acre. The decay process that releases carbon dioxide into the water also uses dissolved oxygen, so adding too much organic matter could reduce dissolved oxygen concentrations to dangerous levels. Dissolved oxygen concentrations must therefore be measured regularly, and the pond aerated, if necessary, to maintain satisfactory oxygen levels.

The above methods are some of the most common way of reducing high pH in fresh water ponds that are not only practical but can easily be localized to fish farming systems.

 

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